Add UI setting to configure log levels for XDCR non-pipeline-specific services.

As part of MB-62507, a new global setting, "genericServicesLogLevel," has been introduced to allow the tuning of log levels for non-pipeline-specific services.
Hence there is a need for a section to allow the tuning of settings that can be applied to all the replications.

Below are details regarding the "genericServicesLogLevel" setting:

The expected value is a JSON object, where the keys represent service names and the values correspond to valid log levels.

By default, all non-pipeline-specific services will have their log level set to "Info." Other valid log levels include "Error," "Debug," and "Trace."

Example usage:

curl -X POST -u Administrator:password http://localhost:8091/settings/replications -d 'genericServicesLogLevel={"RemClusterSvc":"Debug","ReplSpecSvc":"Error","BucketTopologySvc":"Debug","CheckpointSvc":"Error"}' 

 
Kindly let us know if you need more details for the same

FYI - A doc ticket(https://issues.couchbase.com/browse/DOC-12456)has been filed to update the REST API documentation as well

Thank you!