instrument LLAP metadata cache with separate counters by format

Followup from HIVE-15665. ORC file tails, Parquet file tails, and ORC stripe tails should be separately counted for jmx/iomem output. Technically cache should know nothing about what bytebuffer is what, so perhaps it should be by key type, and key types should be separated between the 3 more explicitly (including the replacement on Long HDFS inode based keys with 2 separate wrappers for primitive long).