add a test case that uses compilation database

[andrurogerz]

Purpose

Add a lit-based test case for idt that verifies it properly uses a clang compilation database when provided via the -p command line argument.

Overview

• Add a new test source file GlobalIncludes.cc that depends on header file GlobalHeader.h which is located in a new iuncludes sub-directory and defines a public function globalFunction
• Generate a compile_commands.json file as part of testing GlobalIncludes.cc which adds the new includes subdir to the include path during compilation
• Verify idt generates a warning that globalFunction, defined in the included header`, is not annotated as an exported fucntion
• Update lit config to include .cc files when testing

Validation

• Locally verified the test passes on Windows 11
• Verified the new test runs and passes on Linux in CI