Uses `gopls check <files>` as a linter. Tested locally and brings up 149
errors currently for me. I don't think I want to fix them in this PR,
but I would like at least to get this analysis running on CI.
List of errors:
```
modules/indexer/code/indexer.go:181:11: impossible condition: nil != nil
routers/private/hook_post_receive.go:120:15: tautological condition: nil == nil
services/auth/source/oauth2/providers.go:185:9: tautological condition: nil == nil
services/convert/issue.go:216:11: tautological condition: non-nil != nil
tests/integration/git_test.go:332:9: impossible condition: nil != nil
services/migrations/migrate.go:179:24-43: unused parameter: ctx
services/repository/transfer.go:288:48-69: unused parameter: doer
tests/integration/api_repo_tags_test.go:75:41-61: unused parameter: session
tests/integration/git_test.go:696:64-74: unused parameter: baseBranch
tests/integration/gpg_git_test.go:265:27-39: unused parameter: t
tests/integration/gpg_git_test.go:284:23-29: unused parameter: tmpDir
tests/integration/gpg_git_test.go:284:31-35: unused parameter: name
tests/integration/gpg_git_test.go:284:37-42: unused parameter: email
```
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