[table service][python] introduce a python client for table service

[sijie]

Descriptions of the changes in this PR:

Motivation

We need a python client for accessing table service.

Changes

This is the first change for introducing a python client for table service.

• setup the directory structure for the python client
• setup build, lint, test for the client
• implement the admin client for creating/deleting/getting namespaces/streams
• add examples for admin client

Master Issue: #1690

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