sum(distinct) support

[WinkerDu]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

For now, DataFusion hasn't support sum(distinct) yet. Though optimizer SingleDistinctToGroupBy (#1315) supports single distinct usage, there are more SQL scenes have not been covered.
For example, run the following unit test,

#[tokio::test]
async fn query_sum_distinct() -> Result<()> {
    let schema = Arc::new(Schema::new(vec![
        Field::new("c1", DataType::Int64, true),
        Field::new("c2", DataType::Int64, true),
    ]));

    let data = RecordBatch::try_new(
        schema.clone(),
        vec![
            Arc::new(Int64Array::from(vec![
                Some(0),
                Some(1),
                None,
                Some(3),
                Some(3),
            ])),
            Arc::new(Int64Array::from(vec![
                None,
                Some(1),
                Some(1),
                Some(2),
                Some(2),
            ])),
        ],
    )?;

    let table = MemTable::try_new(schema, vec![vec![data]])?;
    let ctx = SessionContext::new();
    ctx.register_table("test", Arc::new(table))?;

    let sql = "SELECT AVG(c1), SUM(DISTINCT c2) FROM test";
    let actual = execute_to_batches(&ctx, sql).await;
    Ok(())
}

then error raises like

NotImplemented(\"SUM(DISTINCT) aggregations are not available\") at Creating physical plan for 'SELECT AVG(c1), SUM(DISTINCT c2) FROM test': Projection: #AVG(test.c1), #SUM(DISTINCT test.c2)\n  Aggregate: groupBy=[[]], aggr=[[AVG(#test.c1), SUM(DISTINCT #test.c2)]]\n    TableScan: test projection=Some([0, 1])

Describe the solution you'd like
Introduces expressions::DistinctSum into DF

• Maintains a HashSet to record unique numeric list, update HashSet when new item input.
• Aggregate state stores in ScalarValue::List, which Built from HashSet.
• During Final aggregate, evaluate DistinctSum by computing sum from numeric stored in HashSet

Describe alternatives you've considered
No.

Additional context
No.