add stake program functionality #863

Job	Run time
lint	1m 9s
tests (tests/integration/test_async_http_client.py)	1m 29s
tests (tests/integration/test_async_token_client.py)	1m 32s
tests (tests/integration/test_http_client.py)	1m 34s
tests (tests/integration/test_token_client.py)	1m 38s
tests (tests/integration/test_websockets.py)	2m 44s
tests (tests/integration/test_recent_performance_samples.py)	2m 22s
tests (tests/integration/test_memo.py)	1m 35s
tests (tests/unit)	1m 0s
tests (src)	51s
test	1s
coverage	55s
	16m 50s

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