devel/py-typeshed-client: Add py-typeshed-client 2.7.0

typeshed-client provides a way to retrieve information from typeshed and from
PEP 561 stub packages.

Example use cases:

• Find the path to the stub file for a particular module.
• Find the names defined in a stub.
• Find the AST node that defines a particular name in a stub.

Projects for which typeshed_client could be useful include:

• Static analyzers that want to access typeshed annotations.
• Tools that check stubs for correctness.
• Tools that use typeshed for runtime introspection.