Summary:
For tiered storage project, we need to know the block read count and read bytes of files with different temperature. Add FileIOByTemperature to IOStatsContext and collect the bytes read and read count from different temperature files through the RandomAccessFileReader.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8710

Test Plan: make check, add the testing cases

Reviewed By: siying

Differential Revision: D30582400

Pulled By: zhichao-cao

fbshipit-source-id: d83173de594374fc8404af5ce93a6a9be72c7141