fix: ECDSA verify should not panic when signature not reduced

[jonathanpwang]

Finding by @lispc

Description of Fix

• (style) rename previous IntMod::assert_unique to IntMod::assert_reduced and move the implementation using iseqmod into macro since it's specific to the use of special intrinsic.
• Add new is_reduced() -> bool that checks if an integer representation is less than the modulus. Does simple byte-wise comparison check.
• Update ECDSA verify and recover functions so it returns Error when r or s are not in [1,n].

Closes INT-3517

[github-actions]

group	app.proof_time_ms	app.cycles	app.cells_used	leaf.proof_time_ms	leaf.cycles	leaf.cells_used
verify_fibair	(-16 [-1.2%]) 1,269	334,136	17,905,035	-	-	-
fibonacci_program	(-40 [-1.5%]) 2,651	1,500,096	51,485,167	-	-	-
regex_program	(+11 [+0.1%]) 7,770	4,140,164	167,389,450	-	-	-
ecrecover_program	(-7 [-0.5%]) 1,437	295,291	15,588,656	-	-	-
pairing	(+29 [+0.6%]) 4,717	1,711,640	92,585,975	-	-	-

Commit: aae214a

Benchmark Workflow