VS: Honor VS_TOOL_OVERRIDE for known source file types too

Visual Studio Generator: The `VS_TOOL_OVERRIDE` source file property
would previously only be respected for file types that CMake didn't know
how to build out of the box. This change allows the user to override how
any source file is built with a custom build tool, even ones with
standard/recognized extensions such as `.cxx`, `.idl`, etc.

Fixes: #26336
6 files changed