Extend PASS and DROP opcode encoding to support incremental counter

This commit implements COUNT opcode by adding support for incremental
counters to the PASS and DROP opcodes. If counter number is present in the
instruction, the apf_interpreter will increment the relevant counter and
return PASS/DROP immediately, skipping over subsequent instructions.

* design doc: go/apf-v6-proposal

Bug: 293811969
Test: TH
Change-Id: I2430719782a384ad9a7147e42c447ec797e66c21
2 files changed