Context

This merge request is a follow up from !6223 (merged), which seperated filters plug-in and RPC plug-in in a new module Shell_plugin.

This MR move the metrics plugin, defined in Shell_metrics, in Shell_plugin, for consistency.

It also renames lib_plugin/Metrics_plugin to lib_plugin/Metrics for more consistency.

Manually testing the MR

Run a sandbox node with --metrics-addr :1234
Activate alpha
Run a transfer and bake a new block
Run curl http://localhost:1234/metrics |grep gas or curl http://localhost:1234/metrics |grep round and check that the values are correct

Document the interface of any function added or modified (see the coding guidelines)
Document any change to the user interface, including configuration parameters (see node configuration)
Provide automatic testing (see the testing guide).
For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
Select suitable reviewers using the Reviewers field below.
Select as Assignee the next person who should take action on that MR

Edited Sep 09, 2022 by Killian Delarue