This test checks diagnostics on files that are strange for one reason or
another.

Note(rfindley): ported from the old marker tests. I'm not sure why these were
written originally.

-ignore_extra_diags is required because the marker framework fails for
noparse.go, and we therefore can't match the EOF error.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests

go 1.18
-- %percent/perc%ent.go --
package percent //@diag("percent", re"No packages")

-- noparse/noparse.go --