…rios (COM, C++/CLI, custom component host) could try to load coreclr from CWD

There is a fallback for apps with no .deps.json where the host will consider the app directory for loading coreclr. In component hosting scenarios, we do not have an app path / directory. We were incorrectly going down the path of looking for coreclr next to the empty app directory, which resulted in looking in the current directory.

This change skips that path for libhost scenarios. It also adds checks that the paths we determine for loading coreclr, hostpolicy, and hostfxr are absolute.

…-merge-8.0-2025-06-10-1311