[SEDONA-509] Add Single Statistic version of RS_SummaryStats

[prantogg]

Did you read the Contributor Guide?

• Yes, I have read Contributor Rules and Contributor Development Guide

Is this PR related to a JIRA ticket?

• Yes, the URL of the associated JIRA ticket is https://issues.apache.org/jira/browse/SEDONA-509. The PR name follows the format [SEDONA-XXX] my subject.

What changes were proposed in this PR?

• Adds raster accessor RS_SummaryStats to return a single statistic based on statType parameter.
• Renames multi-stat version RS_SummaryStats to RS_SummaryStatsAll.

How was this patch tested?

• Passes new and existing tests

Did this PR include necessary documentation updates?

• Yes, I am adding a new API. I am using the current SNAPSHOT version number in since vX.Y.Z format.