Remove wavm

[phlax]

Our wavm build compiles its own llvm libs

This requires a lot of ci resources, and breaks updating llvm

We could either unbreak the llvm update or potentially just use prebuilt llvm libs, but in offline conversations it was suggested we might not need the wavm build at all as we have other wasm engines compiled with llvm

[phlax]

cc @mpwarres @lizan @kyessenov @PiotrSikora

[PiotrSikora]

SGTM, there are other LLVM-based runtimes (WAMR, WasmEdge) that are actively maintained and supported by Proxy-Wasm and Envoy.

[phlax]

i have started to do this as it will allow us to remove the additional llvm dependency that we currently pull in and compile

one thing im wondering tho is whether we need any kind of deprecation period on this or we can just remove

[phlax]

the other thing im realizing is that wamr is using the same compiler setup so removing wavm doesnt by itself resolve my initial issue