[enhancement](Nereids)support count, min and avg function

[yinzhijian]

Proposed changes

Issue Number: close #xxx

Problem Summary:

1. add count function
2. add min function
3. add avg function

Checklist(Required)

1. Does it affect the original behavior:
   • Yes
   • No
   • I don't know
2. Has unit tests been added:
   • Yes
   • No
   • No Need
3. Has document been added or modified:
   • Yes
   • No
   • No Need
4. Does it need to update dependencies:
   • Yes
   • No
5. Are there any changes that cannot be rolled back:
   • Yes
   • No

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[jackwener]

LGTM

[github-actions]

PR approved by anyone and no changes requested.

[924060929]

good job, could you add some regression test suite in regression-test/suites/ssb_sf1/nereids/ like this?

suite('test_nereids_aggregate_function') {
    // use regression_test_ssb_sf1 database, compute ssb database by suite directory
    String realDb = context.config.getDbNameByFile(context.file)
    // get parent directory's group
    realDb = realDb.substring(0, realDb.lastIndexOf("_"))

    sql "use ${realDb}"

    sql 'set enable_nereids_planner=true'
    // nereids need vectorized
    sql 'set enable_vectorized_engine=true'

    qt 'select count(*), count(l.*), count(1), count(lo_orderkey), count(l.lo_orderkey), min(lo_revenue), min(l.lo_revenue), avg(lo_revenue), avg(l.lo_revenue) from lineorder as l'
}

[morrySnow]

we need to handle count(1) and count(*) in PruneAggChildColumns.

[924060929]

LGTM