Extract find_package calls from CMake build scripts

[nightlark]

Add a query that pulls out the find_package calls from CMake build scripts. This will give a package name (or a variable whose value would need to be determined...) that we could then search for a corresponding package in a Linux dataset for something that provides a Find.cmake, Config.cmake, or <lowercase_package_name>-config.cmake file.

If a project follows good practices like allowing users to point the build at an external copy of any vendored libraries, for our symbols data set this could give a way to avoid claiming that functions in a vendored piece of code are part of the project doing the vendoring.