code generated with `import x "."` fails strict deps checks

Current versions of mockgen (and probably other tools) generate code with imports like:

```
import (
x "."
...
)
```

That isn't allowed by rules_go's strict dependencies check, but doesn't actually require a new dependency.

Example error:

```
GoCompile: missing strict dependencies:
/private/var/tmp/_bazel_jmhodges/ee957dabdee1b1a9e1f2fe90369cf80f/sandbox/darwin-sandbox/685/execroot/founding/bazel-out/darwin-fastbuild/bin/go/path/to/mock_test.go: import of "."
```

Start by reproducing the strict-dependencies failure from the generated mock_test.go example using mockgen output containing import ".". Trace how rules_go processes that import during GoCompile and determine why it is treated as a missing dependency. Done means generated code with this import passes strict dependency checks without requiring a new dependency.

Written by the indexing model from the issue text.