Ambari support for bucket caching parameter - hbase.bucketcache.ioengine

In order to utilize SSD as a L2 (bucket) cache, we specify a file location to hbase.bucketcache.ioengine parameter.

hbase.bucketcache.ioengine=file:<filepath>

The directory location specified to the above parameter could be non-existent or non-accessible.

Since ambari-agent runs with root permissions, the proposed change here is to read the 'hbase.bucketcache.ioengine' parameter from hbase configuration and see if it points to a file location (by looking at file: prefix).
In case ioengine points to a file, ambari-agent should create the underlying directory and assign appropriate permissions to hbase:hadoop user.