Strict rules that check dependencies and type annotations

Will we have strict rules that check for deps and type annotations? i.e. `py_strict_library`, `py_strict_binary`, `py_strict_test`.

Start by reading the issue discussion and the named py_strict_library, py_strict_binary, and py_strict_test examples. The scope is not yet defined; done would require an agreed behavior for dependency and type-annotation checks before implementation can be assessed.

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