[clang] [lld] [llvm] [Support] Add ToolSession for in-process tool invocation (PR #221996)

[Anutosh Bhat via cfe-commits]

anutosh491 wrote:

Thanks for the reviews here. Let me wait till End of Day for any more comments on this after which we can take it in. Thanks all again !

https://github.com/llvm/llvm-project/pull/221996