Stability tests (multiple consecutive payments to same offer)

[mrfelton]

This pull request includes changes to update the configuration and Dockerfile, increase the channel capacity, and add a new test file. The most significant changes are the addition of a new protocol in the configuration file, the update of the Dockerfile to use a different source for the lndk library, the increase of the channel capacity in the initialization script, and the addition of a new test file for payment stability.

Configuration Updates:

• conf/lnd/lnd.conf: Added protocol.wumbo-channels=true to enable the use of channels that can accommodate larger amounts of Bitcoin.

Dockerfile Updates:

• docker/lndk/Dockerfile: Updated the LNDK_REF and LNDK_SOURCE arguments to use a different source for the lndk library, and modified the git clone command to use the LNDK_SOURCE environment variable. [1] [2]

Channel Capacity Increase:

• scripts/init.sh: Increased the channel capacity from 10,000,000 to 15,000,000 and the pushed amount from 5,000,000 to 7,500,000 in the openchannel and fundchannel commands.

New Test File:

• test/test04_payments_ldknode_stability.bats: Added a new test file to check the stability of payments to the LDK node. The test makes multiple consecutive payments and checks if they are successful.