feat(web): add named extractCss option in Rollup executor

[radulle]

In Rollup rollup-plugin-postcss has option of
named extracted css file which can be utilized
by just passing a string to extractCss option.
This does not affect existing functionality.

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✅ Successfully ran 12 targets

• nx affected --target=build --base=f7a61dc2f224dae46eee85b925bfc1d883a4b875 --head=182520fc727839015d9941b558a9476a90ba3369 --parallel=3
• nx affected --target=e2e --base=f7a61dc2f224dae46eee85b925bfc1d883a4b875 --head=182520fc727839015d9941b558a9476a90ba3369 --exclude=e2e-detox,e2e-js,e2e-next,e2e-workspace-create,e2e-workspace-integrations,e2e-workspace-core,e2e-react,e2e-web,e2e-angular-extensions,e2e-angular-core,e2e-cli,e2e-nx-plugin,e2e-cypress,e2e-node,e2e-linter,e2e-jest,e2e-a...
• nx affected --target=e2e --base=f7a61dc2f224dae46eee85b925bfc1d883a4b875 --head=182520fc727839015d9941b558a9476a90ba3369 --exclude=e2e-storybook,e2e-react-native,e2e-detox --parallel=1
• nx affected --target=lint --base=f7a61dc2f224dae46eee85b925bfc1d883a4b875 --head=182520fc727839015d9941b558a9476a90ba3369 --parallel=3
• nx affected --target=test --base=f7a61dc2f224dae46eee85b925bfc1d883a4b875 --head=182520fc727839015d9941b558a9476a90ba3369 --parallel=1
• nx build typedoc-theme
• nx-cloud record -- yarn check-commit
• nx-cloud record -- yarn check-imports
• nx-cloud record -- yarn depcheck
• nx-cloud record -- yarn documentation
• nx-cloud record -- yarn nx format:check --base=f7a61dc2f224dae46eee85b925bfc1d883a4b875 --head=182520fc727839015d9941b558a9476a90ba3369
• nx-cloud record -- yarn nx workspace-lint

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Name	Status	Preview	Updated
nx-dev	✅ Ready (Inspect)	Visit Preview	Jun 15, 2022 at 1:14PM (UTC)

[radulle]

If accepted and merged I'd update docs too.

[jaysoo]

Looks good, I can merge once docs are updated with yarn documentation.

[github-actions]

This pull request has already been merged/closed. If you experience issues related to these changes, please open a new issue referencing this pull request.