Add script to create a Mixed Build

Run the build script with the location of the GSI build, device build,
output, and checkvintf tool.

Bug: 68327258
Test: Run script with sailfish and aosp artifacts.
Merged-In: Ic33dccae26bd70e90badf758266492c9b69eebea
Change-Id: Ic33dccae26bd70e90badf758266492c9b69eebea
1 file changed