document which lints are in core and recommended

[devoncarew]

• document which lints are in core and recommended
• fix add the current set of core and recommended lints to the readme.md file #128 and README links to anywhere but this package's list of lint rules #50

This PR generates the list of list in core and recommended into the readme, and verifies that the list is up-to-date on the CI. It does add dart code to the repo, but only in tool/, and keeps the check that we don't inadvertently add code to lib/.

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@pq for review; @mit-mit for changes to the readme (nothing semantic)

@parlough for fyi re: linking to the https://dart.dev/lints/<code> urls

[devoncarew]

[pq]

🔥

Nice!

[parlough]

Love it!