[Workspace module] river tag support

[pinkcreeper100]

Is your feature request related to a problem? Please describe. i'm looking to switch to river at some point but would like to keep the majority of the other parts of my setup, including the bar, and from what i can see, there is no support for river's tag system

Describe the solution you'd like support for river's tag system

Additional notes/links https://codeberg.org/river/wiki/src/branch/master/pages/How-tags-work.md