Adding example get_client_by_address.py

[adamgross42]

This is somewhat related to #4. I have a fitness machine that doesn't produce the correct advertisement data, but it still produces FTMS data that is readable by other applications. It can be picked up by this library, at least partially, but it needs to bypass the code that inspects the advertisement by first building a client with Bleak, as mentioned here.

I haven't been able to read FtmsEvents events from the machine, so more examples of using get_client() may still be helpful.

To use this script, run: $ pyftms_get_client.py --address xx:xx:xx:xx:xx:xx