Created an Orderfile go file for the build system.

In addition, I added a test file to check if flags are added and propagated correctly.

Test: mma build/soong
Output: #### build completed successfully (07:24 (mm:ss)) ####

For testing with an actual binary or shared library, steps are in this
README:
https://android.googlesource.com/toolchain/pgo-profiles/+/refs/heads/main/orderfiles/README.md

Change-Id: Idcf169156ef691bcacb8adc92828ef09450085f8