Feature request: explore WASM-based migrations

[mfridman]

It'd be nice if users didn't have to build their own goose binaries just to get the benefits of Go migrations.

Imagine if you could write something like this:

migrations
├── 00001_users_table.sql
├── 00002_posts_table.sql
└── 00003_backfill.wasm

Where migration version 3 is a "wasm migration".

I think there's an opportunity for a neat plugin system, so this issue aims to gather feedback and explore various ideas.