[Spaces] Add multiple Spaces

[tbsbdr]

Pre-submission Checks

• [X] I checked for similar issues, but could not find any. I also checked the closed issues. I could not contribute additional information to any existing issue.
• [X] I will take the time to fill in all the required fields. I know that the bug report may be dismissed otherwise due to lack of information.

Feature description

Userstory: As a new employee who was added to multiple Spaces subsequently, I want to quickly access all the Spaces’ files via my Windows Explorer so that I can start working on those files in my familiar Windows-context.

Proposed solution

Step 1

• Synced Spaces show Space image (Square, cropped) or Space placeholder icon like: remix icon "Function fill" or material icon "Grid view"
• Rename button "Add a Space" -> "Add or remove Space"
• Click on "Add or remove Space" opens Dialog

Step 2

• Headline: "Add or remove Space"
• Copytext: "Select a Space to sync it your default folder."
• Help-Link Label(+ Icons for External link): Learn more
• Help-Link Target: to be defined. If we don't have any further help documented, let's skip the Help-Link
• Spaces list shows also Spaces, that are already nsync 🕺
• one or many Space can get selected
• Selection is indicated ex. via checkbox
• Column "Space" shows Space Image/Placeholder, Space Title, Space Subheadline and weblink "Open in Web" incl. icon that indicates "external link"
• Column "Action" (not part of this story): add folder sync pair
• click on "Open in Web" opens the respective Space Frontpage in the browser
• Row-background could be slightly alternated so that rows can be distinguished better
• Click on "Apply": Syncs selected Spaces to the default sync folder.

Synced Spaces are shown (pre-selected)

Select multiple Spaces

Step 3

Selected Spaces are synced to the default sync folder

Alternative solutions you considered

See https://github.com/owncloud/client/issues/10047 as a (hopefully) not so expensive approach.

Additional context

No response

[tbsbdr]

cc @hodyroff

[TheOneRing]

We need to discuss this feature