[backport#15638] [build] Move rpc utility methods to rpc/util

Summary:
Moves the following utility methods to rpc/util and moves that unit to
libbitcoin_common so they can be accessed by all libraries.

• RPCTypeCheck
• RPCTypeCheckArgument
• RPCTypeCheckObj
• AmountFromValue
• ParseHashVParseHashO
• ParseHexV
• ParseHexO
• HelpExampleCli
• HelpExampleRpc

https://github.com/bitcoin/bitcoin/pull/15638/commits/1acc61f8746bc6efb905e121a9f607c4f5982b35

Depends on D5967

This is a partial backport of Core PR15638

Test Plan:

ninja check check-functional

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D5979