Find and replace all nolint instances refering to the `lll` linter and
replace with `ll` which is the name of our custom version of the `lll`
linter which can be used to ignore log lines during linting.
The next commit will do the configuration of the custom linter and
disable the default one.
This commit enhances the itest LND node harness to include support for
the new `HtlcModifier` RPC endpoint.
At the same time we move another method to the correct file.
