Convert CoalesceExec to native implementation.

[guixiaowen]

Spark sql demo：

select /*+ COALESCE(1) */ a, '123' from bigdata_qa.huohun_record_text_v3_2223444

Physical Plan

Coalesce 1
+- NativeProjectExec [a#0, 123 AS 123#2]
+- InputAdapter [#0]
+- NativeOrcScan bigdata_qa.huohun_record_text_v3_2223444 (FileScan orc bigdata_qa.huohun_record_text_v3_2223444[a#0] Batched: true, DataFilters: [], Format: ORC, Location: InMemoryFileIndex(1 paths)[hdfs://DClusterNmg8/user/prod_bigdata_qa/bigdata_qa/hive/bigdata_qa/ns..., PartitionFilters: [], PushedFilters: [], ReadSchema: struct<a:string>)

Convert CoalesceExec to native implementation.

[ShreyeshArangath]

@guixiaowen will you be working on this?