This commit adds wallet-tool, a tool for creating and interacting with
wallet files. Original implementation was by Jonas Schnelli
<dev@jonasschnelli.ch> with modifications by John Newbery
<john@johnnewbery.com>
* [tests] Add wallet-tool test
Original tests by João Barbosa <joao.paulo.barbosa@gmail.com>
Additional contribution by John Newbery <john@johnnewbery.com>
This is a backport of Core PR13926