feat: add separate flag for metrics

[AntiTyping]

Refactors debug and metrics servers into two separate servers

• adds --enable-metrics-server

• uses 127.0.0.1 as the default address for debug and metrics servers

• uses port 5184 as the default port for metrics server

• adds metrics-listen-addr setting to config.yaml

• rly config init will generate the following config

• renamed api-listen-addr to debug-listen-addr

• renames --debug-addr to --debug-listen-addr to be consistent with config

  global:
  debug-listen-addr: 127.0.0.1:5183
  metrics-listen-addr: 127.0.0.1:5184
  ...

• [x] manually test the relayer to make sure it works today

• [x] add unit tests to make sure it works today and in the future

• [ ] should we deprecate old settings and have them still work

[freak12techno]

Just saying, 9100 is a default port for node_exporter, which is widely used everywhere for HW metrics collection, so it might clash.