Improve TypeScript package install experience

[Timer]

This change will prompt the user about missing packages using the same DX instead of two separate code paths.

[github-actions]

Stats from current PR

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	zeit/next.js canary	Timer/next.js fix-ts-setup-dx	Change
Build Duration	15.3s	15s	-226ms
node_modules Size	41.2 MB	41.2 MB	-62 B
Total Bundle (main, webpack, commons) Size	210 kB	210 kB	✓
Total Bundle (main, webpack, commons) gzip Size	68.8 kB	68.8 kB	✓
Client _app Size	2.39 kB	2.39 kB	✓
Client _app gzip Size	1.08 kB	1.08 kB	✓
Client _error Size	8.81 kB	8.81 kB	✓
Client _error gzip Size	3.31 kB	3.31 kB	✓
Client pages/index Size	288 B	288 B	✓
Client pages/index gzip Size	222 B	222 B	✓
Client pages/link Size	4.83 kB	4.83 kB	✓
Client pages/link gzip Size	2.07 kB	2.07 kB	✓
Client pages/routerDirect Size	411 B	411 B	✓
Client pages/routerDirect gzip Size	296 B	296 B	✓
Client pages/withRouter Size	393 B	393 B	✓
Client pages/withRouter gzip Size	280 B	280 B	✓
Client main Size	24.3 kB	24.3 kB	✓
Client main gzip Size	7.98 kB	7.98 kB	✓
Client commons Size	183 kB	183 kB	✓
Client commons gzip Size	59.5 kB	59.5 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	769 B	769 B	✓
Base Rendered Size	1.34 kB	1.34 kB	✓
Build Dir Size	792 kB	792 kB	✓

Click to expand serverless stats

	zeit/next.js canary	Timer/next.js fix-ts-setup-dx	Change
Build Duration	15.9s	15.7s	-197ms
node_modules Size	41.2 MB	41.2 MB	-62 B
Total Bundle (main, webpack, commons) Size	210 kB	210 kB	✓
Total Bundle (main, webpack, commons) gzip Size	68.8 kB	68.8 kB	✓
Client _app Size	2.39 kB	2.39 kB	✓
Client _app gzip Size	1.08 kB	1.08 kB	✓
Client _error Size	8.81 kB	8.81 kB	✓
Client _error gzip Size	3.31 kB	3.31 kB	✓
Client pages/index Size	288 B	288 B	✓
Client pages/index gzip Size	222 B	222 B	✓
Client pages/link Size	4.83 kB	4.83 kB	✓
Client pages/link gzip Size	2.07 kB	2.07 kB	✓
Client pages/routerDirect Size	411 B	411 B	✓
Client pages/routerDirect gzip Size	296 B	296 B	✓
Client pages/withRouter Size	393 B	393 B	✓
Client pages/withRouter gzip Size	280 B	280 B	✓
Client main Size	24.3 kB	24.3 kB	✓
Client main gzip Size	7.98 kB	7.98 kB	✓
Client commons Size	183 kB	183 kB	✓
Client commons gzip Size	59.5 kB	59.5 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	769 B	769 B	✓
Serverless pages/link Size	340 kB	340 kB	✓
Serverless pages/link gzip Size	87.3 kB	87.3 kB	✓
Serverless pages/index Size	331 kB	331 kB	✓
Serverless pages/index gzip Size	84.9 kB	84.9 kB	✓
Serverless pages/_error Size	331 kB	331 kB	✓
Serverless pages/_error gzip Size	84.6 kB	84.6 kB	-1 B
Serverless pages/routerDirect Size	332 kB	332 kB	✓
Serverless pages/routerDirect gzip Size	84.9 kB	84.9 kB	-1 B
Serverless pages/withRouter Size	332 kB	332 kB	✓
Serverless pages/withRouter gzip Size	84.8 kB	84.8 kB	✓
Build Dir Size	2.29 MB	2.29 MB	✓

[github-actions]

Stats from current PR

Click to expand stats

	zeit/next.js canary	Timer/next.js fix-ts-setup-dx	Change
Build Duration	13.8s	14s	⚠️ +162ms
node_modules Size	41.2 MB	41.2 MB	-62 B
Total Bundle (main, webpack, commons) Size	210 kB	210 kB	✓
Total Bundle (main, webpack, commons) gzip Size	68.8 kB	68.8 kB	✓
Client _app Size	2.39 kB	2.39 kB	✓
Client _app gzip Size	1.08 kB	1.08 kB	✓
Client _error Size	8.81 kB	8.81 kB	✓
Client _error gzip Size	3.31 kB	3.31 kB	✓
Client pages/index Size	288 B	288 B	✓
Client pages/index gzip Size	222 B	222 B	✓
Client pages/link Size	4.83 kB	4.83 kB	✓
Client pages/link gzip Size	2.07 kB	2.07 kB	✓
Client pages/routerDirect Size	411 B	411 B	✓
Client pages/routerDirect gzip Size	296 B	296 B	✓
Client pages/withRouter Size	393 B	393 B	✓
Client pages/withRouter gzip Size	280 B	280 B	✓
Client main Size	24.3 kB	24.3 kB	✓
Client main gzip Size	7.98 kB	7.98 kB	✓
Client commons Size	183 kB	183 kB	✓
Client commons gzip Size	59.5 kB	59.5 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	769 B	769 B	✓
Base Rendered Size	1.34 kB	1.34 kB	✓
Build Dir Size	792 kB	792 kB	✓

Click to expand serverless stats

	zeit/next.js canary	Timer/next.js fix-ts-setup-dx	Change
Build Duration	14.5s	14.2s	-345ms
node_modules Size	41.2 MB	41.2 MB	-62 B
Total Bundle (main, webpack, commons) Size	210 kB	210 kB	✓
Total Bundle (main, webpack, commons) gzip Size	68.8 kB	68.8 kB	-2 B
Client _app Size	2.39 kB	2.39 kB	✓
Client _app gzip Size	1.08 kB	1.08 kB	-1 B
Client _error Size	8.81 kB	8.81 kB	✓
Client _error gzip Size	3.31 kB	3.31 kB	✓
Client pages/index Size	288 B	288 B	✓
Client pages/index gzip Size	222 B	222 B	✓
Client pages/link Size	4.83 kB	4.83 kB	✓
Client pages/link gzip Size	2.07 kB	2.07 kB	⚠️ +1 B
Client pages/routerDirect Size	411 B	411 B	✓
Client pages/routerDirect gzip Size	296 B	296 B	✓
Client pages/withRouter Size	393 B	393 B	✓
Client pages/withRouter gzip Size	280 B	280 B	✓
Client main Size	24.3 kB	24.3 kB	✓
Client main gzip Size	7.98 kB	7.98 kB	-1 B
Client commons Size	183 kB	183 kB	✓
Client commons gzip Size	59.5 kB	59.5 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	769 B	769 B	✓
Serverless pages/link Size	340 kB	340 kB	✓
Serverless pages/link gzip Size	87.3 kB	87.3 kB	-1 B
Serverless pages/index Size	331 kB	331 kB	✓
Serverless pages/index gzip Size	84.9 kB	84.9 kB	-2 B
Serverless pages/_error Size	331 kB	331 kB	✓
Serverless pages/_error gzip Size	84.6 kB	84.6 kB	-1 B
Serverless pages/routerDirect Size	332 kB	332 kB	✓
Serverless pages/routerDirect gzip Size	84.9 kB	84.9 kB	-3 B
Serverless pages/withRouter Size	332 kB	332 kB	✓
Serverless pages/withRouter gzip Size	84.8 kB	84.8 kB	-2 B
Build Dir Size	2.29 MB	2.29 MB	✓