PCC: initial end-to-end integration with Wasmtime's static memories.

[cfallin]

This PR wires up end-to-end support for validating the compilation of accesses to static memories in Wasmtime. It creates "memory types" for the vmcontext struct and the memories it points to, and it adds PCC annotations to the relevant memory pointers. On aarch64 (where instruction semantics for PCC are implemented), this validates a simple i32.load function body with default memory configuration.

Note that facts are not yet propagated through egraph rewrites, so optimization has to be disabled for this to work; that support will come next.

Co-authored-by: Nick Fitzgerald fitzgen@gmail.com

[cfallin]

Just a heads-up that the last commit has a few blessed expected-output changes on the Wasm memory access tests, because we had removed the special case vmctx GV lowering (so there are a few more aliases now). No functional change so I think it should be fine...

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