refactor(explorer): refactor protocol parameters naming in epoch setting component

* Remove `Protocol Parameters` as it's deprecated
* Rename `Next Protocol Parameters` to `Registration Protocol Parameters`
  and use `signer_registration_protocol` as source with a fallback to
  `next_protocol` if missing (for retrocompatibility with old
  aggregators).

Refs: #1966

Author: Alenar

mithril-explorer/src/components/EpochSettings/index.js

@@ -73,12 +73,8 @@ export default function EpochSettings() {
                 <div className="mb-2 ps-3">{epochSettings.epoch}</div>
               </Col>
               <Col xs={12} md="auto">
-                <h5>Protocol Parameters</h5>
-                <ProtocolParameters className="mb-2" protocolParameters={epochSettings.protocol}/>
-              </Col>
-              <Col xs={12} md="auto">
-                <h5>Next Protocol Parameters</h5>
-                <ProtocolParameters protocolParameters={epochSettings.next_protocol}/>
+                <h5>Registration Protocol Parameters</h5>
+                <ProtocolParameters protocolParameters={epochSettings.signer_registration_protocol ?? epochSettings.next_protocol}/>
               </Col>
             </Row>
           </Container>