Add/update AccECN related statistics and numbers

[rscheff]

Summary

Reserve couters in the tcps struct in preparation
for AccECN, extend the debugging output for TF2
flags, optimize the syncache flags from individual
bits to a codepoint for the specifc ECN handshake.

This is in preparation of AccECN.

No functional chance except for extended debug
output capabilities.

[rscheff]

• rebase to main
• set flags in rack_fsm_fast_output after ecn changes

[rscheff]

• rebase to main, set flags in rsm_fast_output after ecn changes

[rscheff]

• rebase to main