[TSan][Darwin] Add integration tests for dyld interposition

Add integration tests for dyld interposition: DYLD_LIBRARY_PATH and
DYLD_INSERT_LIBRARIES.

DYLD_INSERT_LIBRARIES is also relevant for TSan thread
finalization/destruction sequence in the presence of additional pthread
introspection hooks (libBacktraceRecording.dylib for Xcode 'Queue
Debugging' feature).

rdar://78739125

Differential Revision: https://reviews.llvm.org/D109332