[BOLT] Delta-encode offsets in BAT (#76900)

This change further reduces the size of BAT:
- large binary: to 13073904 bytes (0.34x original),
- medium binary: to 1703116 bytes (0.29x original),
- small binary: to 436 bytes (0.30x original).

Test Plan: Updated bolt/test/X86/bolt-address-translation.test