Plugin discovery and management

[rhuss]

This epic references the tasks / ideas for implementing a plugin discovery and management tooling in addition to the homebrew mechanism that we currently support.

• kn plugin management #1386
• New plugin "kn-plugin-search" for plugin discovery #1604
• Improve knb test coverage and docs #1231
• Release kn as a kubectl plugin #1368
• Package Manager Option for Windows Installation #1080
• Publish kn with inlined plugins in nightly builds #1584
• Viability and scope of Knative Catalog FT community#1127

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[rhuss]

/approve
/lgtm