Add an option to `func init` for language version

Described by https://github.com/Azure/azure-functions-core-tools/pull/3088#discussion_r915148607. The `--target-framework` option was added to the `func init` command to add support for .NET 7 templates. However, it would be great to have something more generic for other, non-.NET languages.

Start with the linked pull request discussion and the existing `func init` handling for `--target-framework`. Determine how a generic language-version option should apply to non-.NET languages and identify the template paths or command entry points involved. Done means `func init` can use the option for the intended language templates without relying on a .NET-specific name.

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