Allow `wasi_snapshot_preview1.reactor.wasm` to be configurable.

[jamesstocktonj1]

Description

We currently have a scenario where we need to have slightly older wit versions (e.g. wasi:clocks/wall-clock@0.2.0 etc.) but componentize-go comes packed with a reactor which outputs @0.2.6. In my case I re-built with version v24.0.4 of the wasi_snapshot_preview1.reactor.wasm and got the required wit versions.

Proposal

We could potentially add this as a flag for configuration e.g.

componentize-go build --wasm-snapshot <path to snapshot>

Which would default to the included version if no path is specified.