This removes the dependency on clangDriver from clangFrontend and
flangFrontend.
This refactoring is part of a broader effort to support driver-managed
builds for compilations using C++ named modules and/or Clang modules.
It is required for linking the dependency scanning tooling against the
driver without introducing cyclic dependencies, which would otherwise
cause build failures when dynamic linking is enabled.
In particular, clangFrontend must no longer depend on clangDriver
for this to be possible.
This change was discussed in the following RFC:
https://discourse.llvm.org/t/rfc-new-clangoptions-library-remove-dependency-on-clangdriver-from-clangfrontend-and-flangfrontend/88773
3773bbe9e7