[spark] Improve write table plan explain string

[ulysses-you]

Purpose

For example: explain insert into table ...

before:

== Physical Plan ==
AppendDataExecV1 SparkTable(org.apache.paimon.table.PrimaryKeyFileStoreTable@55b12c21), Project [id#287L AS id#290L, (id % 3)#289L AS c1#291L, id#288 AS c2#292], org.apache.spark.sql.execution.datasources.v2.DataSourceV2Strategy$$Lambda$4534/0x000000080270fa08@5762dc14, org.apache.paimon.spark.SparkWrite@30ba29cf

after:

== Physical Plan ==
AppendDataExecV1 PrimaryKeyFileStoreTable[default.bucket_t1], Project [id#3L AS id#6L, (id % 3)#5L AS c1#7L, id#4 AS c2#8], org.apache.spark.sql.execution.datasources.v2.DataSourceV2Strategy$$Lambda$2239/0x0000000801fb0d88@13448d2d, table: default.bucket_t1, saveMode: InsertInto, options: {}

Tests

manually test

API and Format

no

Documentation

[wwj6591812]

Why not add a ut?

[JingsongLi]

+1