Ever since we #5913 have been sending invalid reject messages
for transactions and blocks.
test: Add basic test for `reject` code
Extend P2P test framework to make it possible to expect reject
codes for transactions and blocks.
Github-Pull: #7179
Rebased-From: 9fc6ed600320411903d7
Remove necessity to call create_callback_map (as well as the function
itself) from the Python P2P test framework. Invoke the appropriate
methods directly.
- Easy to forget to call it and wonder why it doesn't work
- Simplifies the code
- This makes it easier to handle new messages in subclasses
Github-Pull: #7171
Rebased-From: 2f601d215d
