[clang] [clang][DependencyScanning] Implementation of `CompilerInstanceWithContext` to Improve By-Name Queries (PR #164345)

[Jan Svoboda via cfe-commits]

jansvoboda11 wrote:

This definitely needs some `clang-scan-deps` tests that perform a couple of by-name scans on the same worker.

https://github.com/llvm/llvm-project/pull/164345