Add an EXECUTABLE_METHOD_FILE_OFFSETS flag to mirror ART

This flag shouldn't be needed, as there is an identical flag defined in
the ART module. However, exported flags aren't currently supported in
`cc_aconfig_library`, so the only option is to define two separate flags
and ramp them in tandem.

Bug: 372925025
Flag: android.uprobestats.flags.executable_method_file_offsets
Test: uprobestats-test
Change-Id: I24901f90ca0bb9aceff30116152a947c5bad4216