Use Sorbet typed: strict in all (non-package) files in Homebrew organisation

[MikeMcQuaid]

Verification

• This issue's title and/or description do not reference a single formula e.g. brew install wget. If they do, open an issue at https://github.com/Homebrew/homebrew-core/issues/new/choose instead.

Provide a detailed description of the proposed feature

We should use Sorbet's typed: strict for all (non-package i.e. not casks or formulae) files in the Homebrew organisation.

Some good transition steps will include:

• requiring typed: strict on all new files
• enabling Sorbet in brew test-bot for taps
• using Sorbet in all taps
• finally: requiring typed: strict in all Homebrew/brew and tap files

What is the motivation for the feature?

• Improving the reliability of Homebrew
• Providing additional support to tests to avoiding regressions
• Improving our API documentation

How will the feature be relevant to at least 90% of Homebrew users?

Making Homebrew more reliable.

What alternatives to the feature have been considered?

Not doing this.