Push stats to prometheus

See merge request !132

updated CMake

Sampling output Thread

First stats test

Added Stats argument to enable output

Added DIRENTS and STATS stats, remover mkdir, rmdir, metadata and data

Added Ifdef feature, chunk distribution statistics

Added output to file

Added documentation

Testing stats

Started prometheus stats

Added Ifdef feature, chunk distribution statistics

Added output to file

Sampling output Thread

First stats test

Added Stats argument to enable output

Resolve "Update catch2 release"

Closes #206

See merge request !131

Resolve "Support other KV Databases"

Closes #173

This `MR` adds support for different metadata backends. Actually, `PARALLAX` from `FORTH` is supported as experimental.
`PARALLAX` needs a 8GB file (minimum size) to store metadata. It is created in the `metadir` directory as `rocksdbx` name.
Inside the install script there is a commented line, to modify an internal parameter of `PARALLAX` increasing the key size drom 255 bytes to 4096 (Max PATH name in POSIX). However, `PARALLAX` is not (fully) tested with such values.

This backend should work in all the scenarios, but there are some issues that appear under high load mdtest.

This `MR` includes the optional compilation/dependencies of each of the backends. Testing is generated dynamically from conftest.template depending on the options selected.

This `MR` includes a new argument for the daemon to remove the rootdir/metadir files directories when the daemon is finished. This reduces the data from artifacts when running databases that uses a fixed size file. (i.e., Parallax)

See merge request !110