keysend: Add `maxfee` to keysend for consistency with pay

[s373nZ]

Add maxfee to keysend for consistency with pay

Description

Adds maxfee parameter to keysend with similar functionality of that of pay. Needed to achieve more consistent behavior across API endpoints.

Related Issues

• Closes #7227

Changes Made

• [x] Feature: Adds maxfee parameter to keysend with similar functionality of that of pay.
• [x] Bug Fix: Fixed a minor typo in keysend documentation comments.
• [x] Refactor: Any code improvements or refactoring done without changing the functionality.

Checklist

Ensure the following tasks are completed before submitting the PR:

• [x] Changelog has been added in relevant commit/s.
• [X] Tests have been added or updated to cover the changes.
  • Added a test for plugin parameter format.
  • Added a test in test_pay.py to test parameter validation, keysend over route exceeding maxfee, and keysend w/ maxfee set.
• [x] Documentation has been updated as needed.
• [x] Any relevant comments or TODOs have been addressed or removed.

Additional Notes

• I initially added the parameter directly after the exemptfee param, but realized order must be important for scripts. Regardless, I've added to the end of documented parameters for backward compatibility, yet there is a "hidden" dev_use_shadow param appearing only in the cli documentation which it appears before.

[s373nZ]

TODO:

• [x] Perform a more reproducible build and commit accurately generated files for:
  • contrib/pyln-grpc-proto/pyln/grpc/node_pb2.py
  • ~contrib/pyln-grpc-proto/pyln/grpc/node_pb2_grpc.py~ (wasn't modified after repro build)
  • ~contrib/pyln-grpc-proto/pyln/grpc/primitives_pb2.py~ (wasn't modified after repro build)
• [x] Research more about keysend and the c implementation to be more sure changes are accurate.
• [x] There doesn't seem to be explicitly tests in the pay plugin for maxfee functionality to emulate, but determine whether this feature needs automated testing.

[s373nZ]

Fixed the cln-grpc Rust test. I didn't think a Draft PR would trigger all the CI. Apologies for the build spam.

[s373nZ]

Added tests and fixed some of the logic for default values of the other parameters.

The maxfee handling logic is more or less a duplication of that found in the pay plugin. Perhaps this could be abstracted and shared? Will look into a little further, but I wonder where the appropriate place for that would be...

[s373nZ]

Sacrificed two semicolons to the flake8 gods.

[s373nZ]

Reran mssgen and regenerated the documentation examples as per the docs for good measure. Used the following commands:

PYTHONPATH=contrib/msggen python contrib/msggen/msggen/__main__.py bundle doc/schemas/
PYTHONPATH=contrib/msggen python contrib/msggen/msggen/__main__.py generate

make check-gen-updated

rm -rf /tmp/ltests* && REGENERATE='keysend' VALGRIND=0 TIMEOUT=10 TEST_DEBUG=1 pytest -vvv -s -p no:logging -n 6 tests/autogenerate-rpc-examples.pyrm -rf /tmp/ltests* && REGENERATE='keysend' VALGRIND=0 TIMEOUT=10 TEST_DEBUG=1 pytest -vvv -s -p no:logging -n 6 tests/autogenerate-rpc-examples.py

make

~The CI build is currently failing, but observation suggests this is happening with all PR branches due to something in master. Will keep an eye on the builds and continue to rebase.~ It looks like this change resulted in a successful build. AFAICT this is ready for an initial review.

[s373nZ]

Rebased, regenerated proto code and removed modifications to CHANGELOG.md for Changelog-Added: hint in commit message.

[cdecker]

ACK https://github.com/ElementsProject/lightning/pull/7653/commits/fdd60db630329a95d5ff3c90185913efc6687db2