Merge #10627: fixed listunspent rpc convert parameter

Summary:
e503b2b fixed listunspent rpc convert parameter (tnaka)

Tree-SHA512: 6da1cee8fd8459187825fad47678b36bbf6b4582f03f557c8a48c2c4273d9e12405e8bb6ade02a06e6555419eefb1dc298d4d4781ebb3b6b72743ca6108cb18e

Backport of Core PR10627
https://github.com/bitcoin/bitcoin/pull/10627

Test Plan:

make check
test_runner.py
./bitcoind
./bitcoin-cli listunspent 1 9999999 "[]" true

The last line should return as expected with list_unsafe=true. Before, it would error out with:

error code: -3
error message:
Expected type bool, got string

Reviewers: deadalnix, Fabien, jasonbcox, markblundeberg, O1 Bitcoin ABC, #bitcoin_abc

Reviewed By: deadalnix, O1 Bitcoin ABC, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D3600