Make Wasm the default language for scripts

[lopert]

WHY are these changes introduced?

Fixes https://github.com/Shopify/script-service/issues/4280

WHAT is this pull request doing?

This PR makes it so that when no language is specified in a shopify script create command, we default to a Wasm project as opposed to presenting the language selector.

It does so by

• removing the language question from Script::Form
• pass the option[:language] from the command directly to the create, and default to "wasm" if it is nil.

How to test your changes?

Run shopify script create and observe that no language prompt is provided. The resulting project should be wasm.
Run shopify script create --language=typescript. The resulting project should be typescript

Update checklist

• I've added a CHANGELOG entry for this PR (if the change is public-facing)
• I've considered possible cross-platform impacts (Mac, Linux, Windows).
• I've left the version number as is (we'll handle incrementing this when releasing).
• I've included any post-release steps in the section above.

[andrewhassan]

Didn't 🎩 but code LGTM!

[ErinRenNumber1]

Looks great. Minor nitpick, we should add to the help text "default to wasm". Like this