sanitycheck: add an FSharpLint phase #2907

Job	Run time
macOS--dotnet6-and-mono	6m 43s
macOS--mono-only	11m 3s
windows--dotnet6-and-legacyFramework	3m 8s
macOS--dotnet6-only	1m 51s
windows--legacyFramework-only	13m 28s
linux-github--dotnet-and-mono	1m 59s
linux-github--dotnet-and-newmono	2m 16s
linux-vanilla--stockdotnet6-only	1m 42s
linux-vanilla--stockmono-only	5m 15s
windows--dotnet6-only	4m 15s
linux-vanilla--newmono-only	8m 18s
linux-vanilla--stockdotnet6-and-newmono	2m 26s
linux-vanilla--stockdotnet6-and-stockmono	2m 24s
conventions	0s
snap_pkg	0s
	1h 4m 48s

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