KUDU-613: Cleanup of cache code

This patch moves some classes out of the
anonymous namespace and into the headers
of the cache and nvm_cache files. These
classes will be used by the new SLRU cache.
This path also templatizes the HandleTable class
to be used by both the cache and nvm_cache files.

Change-Id: I506d4577c0ae873b01d7fa4f53846d6fd0f664cf
Reviewed-on: http://gerrit.cloudera.org:8080/21018
Tested-by: Kudu Jenkins
Reviewed-by: Alexey Serbin <alexey@apache.org>
5 files changed