x/tools/gopls: analyze Fuzz targets in the go/analysis/tests analyzer

[hyangah]

Idea came from #46896 (comment)

f.Fuzz takes any (aka interface{}) type but the parameter must be a fuction with no return value whose first argument is *T and whose remaining arguments match the matching testin.F.Add call.

Add an analyzer to detect misuse of Fuzz API.

[hyangah]

We think this is useful outside gopls and we can consider to add this to vet in the future.

[timothy-king]

Roughly a dup of #46218. The suggestion for putting this into go/analysis/passes/tests/tests.go is a good one. The only real reason I can see to delay going into cmd/vet is that cmd/vet is under code freeze ATM.

[findleyr]

Let's close this as a dupe. We can start #46218 in gopls, but I think it eventually belongs in vet.

[findleyr]

Err, as I'm putting together gopls@v0.8.0 planning, I think it would be nice to have a tracking issue for just the gopls part of this. Reopening.