Cranelift: add a config option for alias analysis and redundant-load elimination. (#4349)

This allows for experiments as in here [1] and also generally gives an
option to anyone who is concerned that the extra optimization may be
counterproductive or take too much time. The optimization remains
enabled by default.

[1]
https://github.com/bytecodealliance/wasmtime/pull/4163#issuecomment-1169303683

crates/wasmtime/src/engine.rs

@@ -384,6 +384,7 @@ impl Engine {
             | "machine_code_cfg_info"
             | "tls_model" // wasmtime doesn't use tls right now
             | "opt_level" // opt level doesn't change semantics
+            | "enable_alias_analysis" // alias analysis-based opts don't change semantics
             | "probestack_func_adjusts_sp" // probestack above asserted disabled
             | "probestack_size_log2" // probestack above asserted disabled
             | "regalloc" // shouldn't change semantics