plugin REST API feature: Import workspace to the plugin container

[clarsonneur]

Core feature

Enhance the forjj plugin REST API to upload current plugin mount to the plugin container.
As soon as we can do it, we can:

• eliminate the need to mount it to the forjj plugin container.
• start using tcp instead of socket

Constraints:

• This feature must be optionnal and detected, so that old plugins can still be used but out of any docker clusters context.
  This means if forjj detect we are in a cluster mode (use tcp) and a plugin use an old version of the REST API, forjj should inform that this plugin is incompatible.

• This feature can be implemented before support of docker TCP.

• Forjj must detect the supported plugin REST API.

• The REST API version must change.