Allow niri IPC (niri msg) to reference workspaces by id instead of by index or name

[jarrod574943pharmes]

Due to the volatility of the index I'd like the reference a (unnamed) workspace by its (more stable) id instead of its index.

Affected niri msg action commands:

• focus-workspace
• move-window-to-workspace
• move-column-to-workspace
• move-workspace-to-index
• set-workspace-name
• unset-workspace-name
• move-workspace-to-monitor
• maybe more but these are the ones I've found

The last command move-workspace-to-monitor does currently not support index or name. This should be added too similar to move-window-to-monitor.