[SEDONA-151] Add ST aggregators to Sedona Flink

[jiayuasu]

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 assoicated JIRA ticket is https://issues.apache.org/jira/browse/SEDONA-151. The PR name follows the format [SEDONA-151] my subject.

What changes were proposed in this PR?

1. Add the following aggregation functions to Sedona, just like Sedona Spark

ST_Envelope_Aggr

ST_Union_Aggr

2. enable event time and proc time in all synthetic test data

All test tables now have two time attributes, namely "event_time", "proc_time"

The 2 attributes can be used in Flink window queries.

How was this patch tested?

New tests added. All existing unit tests passed.

Did this PR include necessary documentation updates?

• Yes, I am adding a new API. I am using the current SNAPSHOT version number in since v1.3.0 format.