[BOLT] Delta-encode function start addresses in BAT (#76902)

Further reduce the size of BAT section:
- large binary: to 12716312 bytes (0.33x original),
- medium binary: to 1649472 bytes (0.28x original),
- small binary: to 428 bytes (0.30x original).

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