Add Provenance table to MetricsSqlQueryService

MetricsSqlQueryService creates and exposes table models atop various NiFi capabilities, such as a Processor Status table, Bulletin table, etc.

It would be nice to add a table model for Provenance events as well. Some fields available in SiteToSiteProvenanceReportingTask will not be available to query, as they are built from properties specified in the reporting task itself, and the table model will not have access to them. Also some derivative fields such as "contentURI" may be renamed "contentPath" as a result.