Add NATIVE_DECIMALS & LAMPORTS_PER_SOL constants #864

Job	Run time
lint	1m 8s
tests (tests/integration/test_async_http_client.py)	1m 34s
tests (tests/integration/test_async_token_client.py)	1m 35s
tests (tests/integration/test_http_client.py)	1m 33s
tests (tests/integration/test_token_client.py)	1m 39s
tests (tests/integration/test_websockets.py)	2m 53s
tests (tests/integration/test_recent_performance_samples.py)	2m 28s
tests (tests/integration/test_memo.py)	1m 41s
tests (tests/unit)	50s
tests (src)	1m 2s
coverage	1m 1s
test	1s
	17m 25s

Provide feedback