Add configuration property to allow the history server to delete .inprogress files

The History Server (HS) currently only considers completed applications when deleting event logs from spark.history.fs.logDirectory (since SPARK-6879). This means that over time, .inprogress files (from failed jobs, jobs where the SparkContext is not closed, spark-shell exits etc...) can accumulate and impact the HS.

Instead of having to manually delete these files, maybe users could have the option of telling the HS to delete all files where (now - attempt.lastUpdated) > spark.history.fs.cleaner.maxAge, or just delete .inprogress files with lastUpdated older then 7d?

https://github.com/apache/spark/blob/d6dc12ef0146ae409834c78737c116050961f350/core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala#L467