Plugin doesn't recompile rust code on change, because watchpack never triggers 'aggregate' event

[MaxchilKH]

@wasm-tool/wasm-pack-plugin@1.6.0 doesn't recompile on Rust source code change, which is expected, because Watchpack never triggers 'aggregate' event.

Form what i understand it's happening because according to Watchpacks readme it's not going to trigger one if aggregateTimeout is undefined, but the plugin creates an instance without any options specified.

One possible solution is to move watchpacks initialization into apply and pass it watchOptions from the config. That would also solve issues like #130 and potential issues with setups requiring polling.

$ wasm-pack  --version
wasm-pack 0.10.3