tests: prepopulate SwiftShims dependencies for CAS

[compnerd]

Ensure that we build the dependent modules when pre-populating the CAS as these are required for the modules to function. This allows us to make greater progress towards getting the tests to pass on Windows.

[compnerd]

@swift-ci please smoke test

[cachemeifyoucan]

Thanks.

I am also intended to add a utility script that just builds all the modules (like https://github.com/swiftlang/llvm-project/blob/next/lldb/scripts/clang-explicit-module-build.py but for swift). Most of the tests just need to build dependencies, and very few tests actually want to explicitly run module builds. That might simplifies most of the if conditions here. Do you want to add it or you want me to add the script and transition for you?

[compnerd]

@cachemeifyoucan - sure if you have done that, please go ahead and add the script and transition to it. I am working through the test suite to enable the tests on Windows so we can get the CAS enabled for Swift code on Windows as well.

[compnerd]

CC: @hjyamauchi