Have `Tools/wasm/wasi` look for extracted tarball installs of the WASI SDK

[brettcannon]

While Tools/wasm/wasi looks for /opt/wasi-sdk by default, that's not the natural directory that tarballs of the WASI SDK extract to. It makes sense to support discovery of the appropriate WASI SDK based on the supported WASI SDK version when it's extracted directly into /opt.

Starting with WASI SDK 23, the tarballs went from containing a directory named wasi-sdk-{WASI_SDK_VERSION}.0 to e.g. wasi-sdk-{WASI_SDK_VERSION}.0-x86_64-linux.

Linked PRs

• GH-137243: Have Tools/wasm/wasi detect WASI SDK installs in /opt when the release tarball is extracted #137244
• [3.14] GH-137243: Have Tools/wasm/wasi detect WASI SDK installs in /opt when the release tarball is extracted (GH-137244) #137250

[brettcannon]

@StanFromIreland FYI this isn't a feature as it's a tool update, and thus more of a build thing (but even that's iffy since it doesn't change the build process, it just makes it less clunky).

[StanFromIreland]

Yes, my intention was to mark it as not-a-bug and type-feature is the closest to that.

[brettcannon]

type-feature is the closest to that

The tricky part with "feature", though, is features have to get a PR review, while something like this in Tools/ is exempt from that sort of thing, so the classification is a bit tricky on this.