rpc: change getnewblockhex to take multiple commitments

[delta1]

Modifies the getnewblockhex json rpc call to accept an array of commitments instead of a single commitment. Backwards compatibility is maintained by first parsing as a string for a single commitment.

Adds a new functional test for this rpc call.

[apoelstra]

Concept ACK -- heads up you can make this a non-breaking change by explicitly accepting a string and just converting it to an array internally.

[delta1]

@apoelstra thanks, yeah good point is that preferable?

[apoelstra]

Yes, it's much preferable to keep existing RPC scripts working.

[delta1]

Okay sure will do

[stevenroose]

utACK 1100877

[apoelstra]

./test/functional/rpc_help.py fails now

[delta1]

./test/functional/rpc_help.py fails now

sorry will take a look

[apoelstra]

19:11:17 -bash@camus ~/code/ElementsProject/elements/pr-review e08a86df0e5$ ./test/functional/feature_blocksign.py 
2022-09-06T19:11:19.104000Z TestFramework (INFO): Initializing test directory /tmp/bitcoin_func_test_3ghet7ze
2022-09-06T19:11:19.471000Z TestFramework (INFO): Mining and signing 101 blocks to unlock funds
2022-09-06T19:11:19.476000Z TestFramework (ERROR): Assertion failed
Traceback (most recent call last):
  File "/store/home/apoelstra/code/ElementsProject/elements/pr-review/test/functional/test_framework/test_framework.py", line 128, in main
    self.run_test()
  File "/store/home/apoelstra/code/ElementsProject/elements/pr-review/./test/functional/feature_blocksign.py", line 189, in run_test
    self.mine_blocks(101, False)
  File "/store/home/apoelstra/code/ElementsProject/elements/pr-review/./test/functional/feature_blocksign.py", line 178, in mine_blocks
    self.mine_block(transactions)
  File "/store/home/apoelstra/code/ElementsProject/elements/pr-review/./test/functional/feature_blocksign.py", line 128, in mine_block
    assert_equal(CScript(dummy_struct.vtx[0].vout[0].scriptPubKey).hex(), '6a04deadbeef')
  File "/store/home/apoelstra/code/ElementsProject/elements/pr-review/test/functional/test_framework/util.py", line 62, in assert_equal
    raise AssertionError("not(%s)" % " == ".join(str(arg) for arg in (thing1, thing2) + args))
AssertionError: not(51 == 6a04deadbeef)
2022-09-06T19:11:19.527000Z TestFramework (INFO): Stopping nodes
2022-09-06T19:11:19.583000Z TestFramework (WARNING): Not cleaning up dir /tmp/bitcoin_func_test_3ghet7ze
2022-09-06T19:11:19.583000Z TestFramework (ERROR): Test failed. Test logging available at /tmp/bitcoin_func_test_3ghet7ze/test_framework.log
2022-09-06T19:11:19.583000Z TestFramework (ERROR): 
2022-09-06T19:11:19.583000Z TestFramework (ERROR): Hint: Call /store/home/apoelstra/code/ElementsProject/elements/pr-review/test/functional/combine_logs.py '/tmp/bitcoin_func_test_3ghet7ze' to consolidate all logs
2022-09-06T19:11:19.583000Z TestFramework (ERROR): 
2022-09-06T19:11:19.583000Z TestFramework (ERROR): If this failure happened unexpectedly or intermittently, please file a bug and provide a link or upload of the combined log.
2022-09-06T19:11:19.583000Z TestFramework (ERROR): https://github.com/ElementsProject/elements/issues
2022-09-06T19:11:19.583000Z TestFramework (ERROR): 

[delta1]

@apoelstra all fixed now

[apoelstra]

ACK 5d10ff9