Add `--version` to wabt tools (#1175)
Closes: #1106
Ported versioning system from [Binaryen CMakeLists.txt](https://github.com/WebAssembly/binaryen/blob/dc31b460fef47dfb3415b4ae6276fff4919a03e2/CMakeLists.txt#L10-L23)
```
bin/wasm2c --version
1.0.11-44-g71f883ad
```
Applied to (all) tools in `src/tools/`.
