Remove pervasive use of OnlineSolver constraints in stubs

[RyanGlScott]

Many parts of the stubs code base require OnlineSolver constraints, which are necessary to communicate with an online SMT solver connection. One example of this is the functionOverride function:

stubs/stubs-common/src/Stubs/FunctionOverride.hs

Lines 102 to 108 in f34bfb8

	, functionOverride
	:: forall bak solver scope st fs
	. ( LCB.IsSymBackend sym bak
	, sym ~ WE.ExprBuilder scope st fs
	, bak ~ LCBO.OnlineBackend solver scope st fs
	, WPO.OnlineSolver solver
	)

I suspect that this is an artifact of the code in ambient-verifier, which defined several overrides which require an online solver. That being said, it's unclear to me if we actually need to percolate OnlineSolver constraints everywhere in stubs. Ideally, stubs would be written in a way that is SMT connection–agnostic so that it can work for both offline and online solvers alike. This issue tracks the task of refactoring stubs to make this possible.

[RyanGlScott]

Similar concerns apply to Stubs.Syscall.syscallOverride.