feat: Add manila csi

[okozachenko1203]

• This PR includes manila-csi-plugin deployment. This PR extends magnum.conf by adding [manila_client] section for keystone authtoken. So magnum driver can configure manila_client and use this to interact with sharev2 api.
• magnum doesn't support manila intergration so I override magnum.common.clients.OpenStackClients to include manila method which returns the manila client.
• This PR also makes cinder-csi-plugin and manila-csi-plugin as conditional. i.e. even if labels (cinder_csi_enabled, manila_csi_enabled) are set as true, if the underlying openstack has no enabled endpoints for cinder and manila, it will not install those plugins.

fix: #79

[okozachenko1203]

@mnaser i added comments where requires more attention.

[mnaser]

@okozachenko1203 I previously built a tool here which will 'sync' all the manifests and apply all the changes that we use -- https://github.com/vexxhost/magnum-cluster-api/blob/main/tools/sync-csi-manifests

There are other sync jobs too. I think what I would like is that maybe we extend that script, and we also create a job that runs this script in CI and uses git to make sure that no changes happen, which means that no one made changes that were not implmented in this script and we can 'reliabely' get the manifests by running that script.

The potential second step to this is adding this script into the build script so that the manifestis not bundled in the source code but added in build time like we do for charts.

[okozachenko1203]

@okozachenko1203 I previously built a tool here which will 'sync' all the manifests and apply all the changes that we use -- https://github.com/vexxhost/magnum-cluster-api/blob/main/tools/sync-csi-manifests

There are other sync jobs too. I think what I would like is that maybe we extend that script, and we also create a job that runs this script in CI and uses git to make sure that no changes happen, which means that no one made changes that were not implmented in this script and we can 'reliabely' get the manifests by running that script.

The potential second step to this is adding this script into the build script so that the manifestis not bundled in the source code but added in build time like we do for charts.

I think we can consider keeping diff/patch files instead of writing py script.