Add extra configuration options to gRPC

[ErikDeSmedt]

Pull Request Title

Description

I've added a few configuration options to the gRPC-plugin.

• grpc-ip-address: I've changed the default ip-address to which the gRPC interface will bind from 0.0.0.0 to 127.0.0.1. This new default should be more secure. Users who need to access the gRPC-interface externally can set grpc-ip-address to the port they like. Users can also configure an IPv6 address.
• grpc-scheme: Previously, the gRPC connection only allowed https over mTLS. Configurting mTLS is somewhat cumbersome. Users that only need the gRPC interface locally can now set grpc-scheme=http. This will only work if grpc-ip-address is set to a loopback address (127.0.0.1 or equivalent for IPv6).

Related Issues

• Closes https://github.com/ElementsProject/lightning/issues/7654

Changes Made

• [ x ] Feature: More config options for gRPC interface

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.
• [x] Documentation has been updated as needed.
• [x] Any relevant comments or TODOs have been addressed or removed.

Additional Notes

Any additional information or context about this PR that reviewers should know.

[ErikDeSmedt]

The test_grpc_connect_notification failed in the clang compilation target.

I tried to reproduce the failure locally. To do this I compiled Core Lightning using clang.

CC=clang ./configure

Subsequently, I ran the test a 100 times.

for i={1..100}; do PYTEST_OPTS='-k test_cln_grpc_connect_notification' make pytest; done

I haven't observed a single failure. I'm not convinced the test is actually broken and don't have a way to reproduce

[rustyrussell]

This needs a rebase, now that the grpc-host config option has been included.

@ShahanaFarooqui ?

[rustyrussell]

This needs a rebase, since the grpc-host option is now merged (separately).

[ShahanaFarooqui]

This needs a rebase, since the grpc-host option is now merged (separately).

I did rebase it on grpc-host option but need to rebase again after 7807 merge. I also need to clean up some commits. Working on them right now.