ESQL: Multiple parameters in ungrouped aggs

[nik9000]

Adds support for multiple parameters to ungrouped aggregations.

Relates to #108385

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[nik9000]

This should add support for something like | STATS AGG(foo, bar). It works on my private branch working on FIRST and LAST.

The changes to the generated files pretty much just renaming variables and moving some if statements to methods describing what they are doing.

If the foo or bar are multivalued then the agg receives the combinatorial explosion of the values. That's fine for FIRST and LAST which is what I'm working towards now.

If either foo or bar are null, then the agg receives no values.

[dnhatn]

LGTM. Thanks Nik!

[nik9000]

This is what it looks like for multivalued fields:

  private void addRawVector(LongVector timestampVector, DoubleVector valueVector) {
    state.seen(true);
    for (int i = 0; i < timestampVector.getPositionCount(); i++) {
      long timestampValue = timestampVector.getLong(i);
      double valueValue = valueVector.getDouble(i);
      FirstOverTimeDoubleAggregator.combine(state, timestampValue, valueValue);
    }
  }

  private void addRawBlock(LongBlock timestampBlock, DoubleBlock valueBlock) {
    for (int p = 0; p < timestampBlock.getPositionCount(); p++) {
      if (timestampBlock.isNull(p)) {
        continue;
      }
      if (valueBlock.isNull(p)) {
        continue;
      }
      state.seen(true);
      int timestampStart = timestampBlock.getFirstValueIndex(p);
      int timestampEnd = timestampStart + timestampBlock.getValueCount(p);
      for (int timestampOffset = timestampStart; timestampOffset < timestampEnd; timestampOffset++) {
        long timestampValue = timestampBlock.getLong(timestampOffset);
        int valueStart = valueBlock.getFirstValueIndex(p);
        int valueEnd = valueStart + valueBlock.getValueCount(p);
        for (int valueOffset = valueStart; valueOffset < valueEnd; valueOffset++) {
          double valueValue = valueBlock.getDouble(valueOffset);
          FirstOverTimeDoubleAggregator.combine(state, timestampValue, valueValue);
        }
      }
    }
  }

[nik9000]

Thanks @dnhatn and @idegtiarenko .