Settings: Site sync project settings improvement

[iLLiCiTiT]

Description

Reduce settings of sites for sync server in project settings. Now it shows settings for all providers for each site name and site names must be manually added.

Changes

• added new settings entity sync-server-sites
• entity works as dictionary children based on sync server system settings
• all site names are always available in project settings
  • each site have enabled boolean to know if should be enabled for the project
• other schemas for value are get from providers using get_project_settings_schema

TODO

Use this entity and replace current site item in settings. That require to modify how sync server module uses settings and probably will have to keep backwards compatibility. So it should be done in different PR.

How to test

Change sites in project settings schemas to this:

{
    "type": "sync-server-sites",
    "collapsible": true,
    "key": "sites",
    "label": "Sites",
    "collapsible_key": false
}

File ~/openpype/settings/entities/schemas/projects_schema/schema_project_syncserver.json

[mkolar]

Task linked: OP-1939 Site sync project settings improvement.