perf: pass state variables by value in tco exec handlers

[shuklaayush]

• pass pc, instret and instret_end/max_execution_cost/segment_check_insns by value in execution handlers to get them to be passed in registers
• add likely, unlikely hints for suspension/termination in tco

benchmark comparison

Towards INT-4921

[jonathanpwang]

nit: perhaps it'd be nice to have an inst_inc! or inst_advance!` macro to make these changes more uniform for later

[shuklaayush]

i'll keep this for later when i try to get rid of pc

[jonathanpwang]

Overall it was not as bad as I thought. I do wonder if we could use some more macros to clean up all the places you had to change, but that's another story.

LGTM except the pc, instret fields in VmState should now be private and you should only be allowed to mutate them via some conscious decision via a function.

[github-actions]

group	app.proof_time_ms	app.cycles	app.cells_used	leaf.proof_time_ms	leaf.cycles	leaf.cells_used
verify_fibair	(-5 [-1.8%]) 268	322,610	2,058,654	-	-	-
fibonacci	(-3 [-0.3%]) 1,017	1,500,210	1,060,232	-	-	-
regex	(+9 [+0.3%]) 2,976	4,108,483	13,403,604	-	-	-
ecrecover	(+7 [+0.7%]) 969	140,497	2,275,066	-	-	-
pairing	1,542	1,882,939	23,722,622	-	-	-

Commit: 9242af6

Benchmark Workflow