Re-introduce Radicale

[buxx]

Currently

Calendar system have been removed from v2.0.

Expected

Re-introduce radicale server.

• add Proxy mecanism to tracim
• Update hapic version to support disable_doc
• add radicale launcher with tracimcli caldav start
• add radicale config to developement.ini file.
• add proxy controller for radicale server
• add lib tests for proxy
• add functional test for radicale proxy
• add new endpoint /users/{user_id}/calendar and /users/me/calendar
• add tests for theses endpoints
• add tracimcli caldav calendar create command to create alls calendars
• add debug mode for commands to inspect more clearly issues
• force all user/workspace creation code to user execute on created method
• add calendar creation on_created event for both user and workspace.
• remove caldav_url from user api.
• Make on created event work as hook for event, see Feat: Add Event Mecanism to tracim for user create/user_created #1487
• add calendar_enabled temporary to workspace_api in order to allow frontend to activate/disactivate this.

Issues created (but not resolved) during coding this feature :

• endpoints factorization, see refactor account endpoint code #1478
• use class instead of validators, see Misc: Use Custom Marshmallow field instead of validator. #1477
• removing caldav_url for user in api may broke frontend removing caldav_url for user in api may broke frontend #1486

Problems faced during development are related to trailing slash. Radicale always requires the trailing slash.

TODO :

• implement the on_user_created and add a command which creates the user calendar
• implement the on_warkspace_created and add a command which creates the workspace calendar
• add a tracimcli command which loop on calendars and create/delete an event
• add calendar to list of apps endpoint
• manage endpoint returning calendar labels