Add fallback input option to ensure that fallback is not used

[taiki-e]

Add an option to prevent accidentally installing tools that use fallback for installation.

- uses: taiki-e/install-action@v2
  with:
    tool: <tool>
    # Possible values:
    # - none: disable all fallback
    # - cargo-binstall (default): cargo-binstall (includes quickinstall)
    fallback: none

We could add an option to use cargo-binstall without quickinstall in the future if someone actually wants to use that.

Related discussion: https://github.com/taiki-e/install-action/pull/514

cc @jayvdb

[taiki-e]

Considering there is a proposal to add a non-cargo-binstall fallback (https://github.com/taiki-e/install-action/issues/526) too, I think this option is good as is. We can discuss how to pass additional flags to cargo-binstall in another issue.