opt-in support to INFO log all parameters on error

• The logParamsList parameter (available from Solr 4.7 onwards via SOLR-5672) is useful if full request logging on each of multiple shards is just 'too much' and/or if the content being logged is to be redacted e.g. to only log opaque request identifiers but not request details.
  • A downside of reduced logging is that less detail is available when investigating issues.

• The echoParams parameter controls what information about request parameters is included in the response header.
  • With respect to investating of issues it's worth noting here that echoParams=explicit is the default value and that routine use of echoParams=all would return more details to the client but that details of within-Solr requests e.g. requests using the group.distributed.first and group.distributed.second group parameters would not be captured.

This ticket proposes to add a new parameter, called (say) logAllParamsOnError whose use will result in all parameters being logged on error, irrespective of the presence or value of the logParamsList parameter.