Improve how we find locations of .dylibs and .so files (e.g. SwiftAndJavaJarSampleLib)

[ktoso]

In order to run e.g. the SwiftAndJavaJarSampleLib sample, we do a complicated dance to find all the paths to all the native dynamic libs and libswiftCore as well.

This can be partially simplified.

The lib paths we should get from swiftpm like this:

swift build --show-bin-path -c debug
/Users/ktoso/code/swift-java/.build/arm64-apple-macosx/debug

Next we need to be able to find the libswiftCore.so/dylib in some way less annoying than shell scripting.

We should offer this as a task in gradle or command plugin maybe in swiftpm?