## What changes were proposed in this pull request?
In RuleExecutor, after applying a rule, if the plan has changed, the before and after plan will be logged using level "trace". At times, however, such information can be very helpful for debugging. Hence, making the log level configurable in SQLConf would allow users to turn on the plan change log independently and save the trouble of tweaking log4j settings. Meanwhile, filtering plan change log for specific rules can also be very useful.
So this PR adds two SQL configurations:
1. spark.sql.optimizer.planChangeLog.level - set a specific log level for logging plan changes after a rule is applied.
2. spark.sql.optimizer.planChangeLog.rules - enable plan change logging only for a set of specified rules, separated by commas.
## How was this patch tested?
Added UT.
Closes#22406 from maryannxue/spark-25415.
Authored-by: maryannxue <maryannxue@apache.org>
Signed-off-by: gatorsmile <gatorsmile@gmail.com>
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