Make -Rmodule-loading dump the module search paths

[kubamracek]

It's often useful to understand what are the search paths and what's their order to diagnose module loading issues. This PR adds a dump of search path when -Rmodule-loading is used. Output looks like this (I'm using embedded Swift in this case):

Module import search paths (non system):
  [0] /Library/Developer/CommandLineTools/SDKs/MacOSX14.1.sdk/usr/lib/swift
Framework search paths:
Darwin implicit framework search paths:
  [0] /Library/Developer/CommandLineTools/SDKs/MacOSX14.1.sdk/System/Library/Frameworks
  [1] /Library/Developer/CommandLineTools/SDKs/MacOSX14.1.sdk/Library/Frameworks
Runtime library import search paths:
  [0] /Users/kuba/swift-github-main/build/Ninja-RelWithDebInfoAssert/swift-macosx-arm64/lib/swift/embedded
  [1] /Library/Developer/CommandLineTools/SDKs/MacOSX14.1.sdk/usr/lib/swift
(End of search path lists.)

[rauhul]

This is so helpful thank you!!

[kubamracek]

@swift-ci please test