apply_fixes missing_deps discovery respects visibility

[martis42]

Followup to #18

Currently the feature to automatically add missing direct dependencies does not consider if a discovered dependency is visible to the target under inspection.

Assuming we make no error in matching include statement to target, there are 2 cases we can resolve by implementing this:

• If multiple targets in the dependency tree provide a given header we skip this right now with a warning. With visibility we could potentially decide which target to choose.
• Even if we find only a single dependency, it might be invalid. If aliases are involved we might add a target which breaks the build, although the added dependency provides the required header.

[martis42]

https://bazel.build/query/language#visible