Move RPC registration out of AppInitParameterInteraction

Summary:
Move to AppInitServers. This doesn't have any effects on bitcoin behavior. It
was just strange to have this unrelated code in the middle or parameter
interaction.

This is a backport of Core PR11603 + a bunch of scafolding due to difference in codebases

Depends on D3046

Test Plan:

make check
./test/functional/test_runner.py

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D3047