### What changes were proposed in this pull request?
Rename config "spark.sql.ansi.enabled" to "spark.sql.dialect.spark.ansi.enabled"
### Why are the changes needed?
The relation between "spark.sql.ansi.enabled" and "spark.sql.dialect" is confusing, since the "PostgreSQL" dialect should contain the features of "spark.sql.ansi.enabled".
To make things clearer, we can rename the "spark.sql.ansi.enabled" to "spark.sql.dialect.spark.ansi.enabled", thus the option "spark.sql.dialect.spark.ansi.enabled" is only for Spark dialect.
For the casting and arithmetic operations, runtime exceptions should be thrown if "spark.sql.dialect" is "spark" and "spark.sql.dialect.spark.ansi.enabled" is true or "spark.sql.dialect" is PostgresSQL.
### Does this PR introduce any user-facing change?
Yes, the config name changed.
### How was this patch tested?
Existing UT.
Closes#26444 from xuanyuanking/SPARK-29807.
Authored-by: Yuanjian Li <xyliyuanjian@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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