Set direct/transitive module sets for CppCompileAction without include scanning

[fmeum]

Description

When include scanning is disabled, CppCompileAction never populated its top-level modules nor its discovered (transitive) modules: the former caused getOverwrittenVariables() to fall back to putting every transitive .pcm on the command line, and the latter left ActionExecutionValue without discovered modules for module-producing compiles.

Fix this by computing a suitable upper bound at action construction time when header modules are used without include scanning:

• Top-level modules: the modules of direct dependencies plus the separate module of the current context (except for its own compile), mirroring the exclusions of CcCompilationContext#computeUsedModules. Modules that are only used transitively are found by the compiler through the paths embedded in the direct .pcm files, just as in the include scanning case.
• Discovered (transitive) modules: all transitive modules plus the top-level bound, which are all provided as inputs.

Since the separate module of the current context is not part of the transitive modules, CppCompileActionBuilder now also adds it as an input to all compiles of the context other than its own compile, matching the existing allowedDerivedInputs special case.

Motivation

Fixing header module compilation in Bazel with default settings, i.e., without include scanning.

Build API Changes

No

Checklist

• I have added tests for the new use cases (if any).
• I have updated the documentation (if applicable).

Release Notes

RELNOTES: None

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