[InstallAPI] Set InstallAPI as a standalone tool instead of CC1 action (#82293)

Installapi has important distinctions when compared to the clang driver,
so much that, it doesn't make much sense to try to integrate into it.

This patch partially reverts the CC1 action & driver support to replace
with its own driver as a clang tool.

For distribution, we could use `LLVM_TOOL_LLVM_DRIVER_BUILD` mechanism
for integrating the functionality into clang such that the toolchain
size is less impacted.