[6.2 🍒][Dependency Scanning] On failure to locate a module, attempt to diagnose if binary dependencies contain search paths with this module.

[artemcm]

Cherry-pick of #81919

• Explanation: Unlike with implicitly-built modules (prior to Swift 6 mode), explicitly-built modules require that all search paths be specified explicitly and no longer inherit search paths serialized into discovered Swift binary modules. This behavior was never intentional and is considered a bug. This change adds a diagnostic note to a scan failure: for each binary Swift module dependency, the scanner attempts to execute a dependency scanning query for each serialized search path inside that module. If such diagnostic query returns a result, a diagnostic is be emitted to inform the user that the dependency may be found in the search path configuration of another Swift binary module dependency, specifying which search path contains the "missing" module, and stating that such search paths are not automatically inherited by the current compilation.

• Scope: Builds using explicitly-built modules which encounter a "module not found" error where the missing module may be located on search paths used to build some other Swift module dependency of the current compilation. A common example is a test target which depends on a library target but is missing search paths on some transitive dependencies (via said library target).

• Risk: Low. The added code paths are triggered only in the case of existing compilation failures and attempt to provide more helpful context.

• Problem: rdar://152662336

• Reviewed By: @cachemeifyoucan

• Original PR: [Dependency Scanning] On failure to locate a module, attempt to diagnose if binary dependencies contain search paths with this module. #81919

[artemcm]

@swift-ci test

[nkcsgexi]

Missing search paths is a very common problem when switching from implicit module builds to explicit. We've implemented these actionable diagnostics help folks configure their projects to be EBM-friendly. Also, these new diagnostics aren't risky because we are simply adding more information to an already failing build.