WAVM support

[lrettig]

Investigate using WAVM for JIT compilation of ewasm

cf. ewasm/hera#158

[lrettig]

@jakelang's update from today's standup: Working on getting WABT + WAVM working together

[lrettig]

@jakelang any updates here?

[jakelang]

@lrettig abstraction layer is ready to go, just hoping that it gets merged before i start piling more on the PR. also, this issue is a duplicate of ewasm/hera#158

[lrettig]

@jakelang Thanks for the update. Yes I'm aware that it's a dupe, this repo is more of a high-level PM repo to track all of the testnet-critical tasks via Waffle with links to other tickets, as I added in the task description above.

[lrettig]

@jakelang update from yesterday: figuring out WAVM’s runtime api right now, so i can use it in Hera. going to forget about the cmake stuff for now.

[lrettig]

@jakelang update from Friday: still stuck trying to get WAVM to compile with cmake.