crux-mir doesn't respect --assert-false-on-error

[RyanGlScott]

crux-mir provides an --assert-false-on-error option:

$ cabal run exe:crux-mir -- --help
...
[Crux]                --assert-false-on-error       when translation fails, assert false in output and keep going

However, the implementation of crux-mir never actually does anything with this option:

crucible/crux-mir/src/Mir/Language.hs

Lines 209 to 210 in 06893d7

	--let ?assertFalseOnError = assertFalse mirOpts
	let ?assertFalseOnError = True

(This change was introduced in f9d4f8c.) Similarly, the test suite hard-codes the value here:

crucible/crux-mir/test/Test.hs

Line 182 in 06893d7

let ?assertFalseOnError = True

If we are going through the effort of passing ?assertFalseOnError as an implicit parameter, we ought to make it properly configurable by the user.