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

Add command line option for kreon

Resolve CRTP specific function name

Testing Infrastructure for different databases

add path

Reactivated destructors, kreondb is destroyed to reduce CI space

Returning string_view in fs_data added dbbackend property

Updated Readme and MetatadaFactory

Adding extra options for kreondb, README+CHANGELOG updated

Update .gitlab-ci.yml

updating script test...

Updated dl_dep tests

Kreon test (for metadata) backend.

Add command line option for kreon

Resolve CRTP specific function name

Testing Infrastructure for different databases

add path

Reactivated destructors, kreondb is destroyed to reduce CI space

Returning string_view in fs_data added dbbackend property

Adding extra options for kreondb, README+CHANGELOG updated

updating script test...

Updated dl_dep tests

Remove Kreon - Add Parallax

Add Parallax

Add DockerFile

adding parallaxdb option

Docker update

Missing Parallax hpp

Removed Kreon from code, lib conflicts

Updated Parallax master

Updated DockerFile deps

Reformat

Changed Base

Added ps

Reduced Logging and added ps in docker

Add Path

increase testing timeout

Create options.yml automatically

Updated out tests

Resolve "faccessat2() and getxattr() syscall support missing"

Closes #209

See merge request !130

Added in kernel 5.8

Resolve "Bug: Guided distributor tests are run when turned off"

Closes #208

See merge request !129

Release 0.9.0

See merge request !126

Resolve "Update GekkoFS Wiki for v0.9.0"

Closes #200

See merge request !124

Resolve "Sphinx-Doxygen: private struct/class member are not parsed"

Closes #201

See merge request !125

See PR https://github.com/svenevs/exhale/pull/154

Resolve "Remove boost/algorithm/string.hpp from client"

Closes #197

See merge request !123

Resolve "Remove boost interval_map dependencies"

Closes #195

See merge request !122

Resolve "Automatically generate GekkoFS documentation"

This MR adds a `docs` target to the build system that can be used to automatically generate Sphinx documentation based on ReStructured Text for the project. Additionally, it also processes the source files through Doxygen to generate intermediate XML that can be passed to Sphinx extensions Breathe and Exhale so that GekkoFS classes and functions can be referenced from the Sphinx documentation.

The CI script is also extended to build this documentation and deploy it to the project's site.

Closes #159

See merge request !95