Forward CMake variables to prebuilding dependencies

[sfod]

Issue #, if available:

When prebuilding dependencies, we need to pass certain CMake variables from parent cmake process to child cmake process (e.g. toolchain file or path to C compiler). CMake doesn't provide this functionality out of the box.

Description of changes:

This PR implements a new CMake function that checks CMake cache file and collects variables that may affect build process. aws_prebuild_dependency uses this new function, so no changes are required in the downstream projects.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 83.63%. Comparing base (252e8c2) to head (8f8067c).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1161 +/- ## ======================================= Coverage 83.63% 83.63% ======================================= Files 57 57 Lines 5953 5953 ======================================= Hits 4979 4979 Misses 974 974 ```

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