[feat] sway/workspaces: refer to outputs by their monitor identifier in persistent-workspaces

[ar-turek]

This PR extends the persistent-workspaces functionality in sway/workspaces with an option of pinning workspaces to displays by their output identifiers (basically, the monitor's "make and model", usually given as a vendor/model/serial triple) in addition to their output name (e.g. DP-3, which is unstable and can change between reboots).

That means instead of this:

{
    ...
    "sway/workspaces": {
        ...
        "persistent-workspaces": {
            "1:main": ["DP-2"],
            "2:code": ["DP-2"],
            "3:secondary": ["DP-3"],
            "0:TV": ["HDMI-A-1"]
        }
    },
    ...
}

we can now write this:

{
    ...
    "sway/workspaces": {
        ...
        "persistent-workspaces": {
            "1:main": ["Dell Inc. Dell AW2518H #ASM0cCiovard"],
            "2:code": ["Dell Inc. Dell AW2518H #ASM0cCiovard"],
            "3:secondary": ["AOC 24P4CV XL9RAHA000298"],
            "0:TV": ["Philips Consumer Electronics Company Philips FTV 0x01010101"]
        }
    },
    ...
}

and even if the outputs are renamed after a reboot the workspaces will still be assigned to correct displays.

[ar-turek]

Please let me know if you'd like me to make an update to the wiki as well, if/when this is merged - I'm not sure if it's possible to stage wiki changes as PRs as well.

[ar-turek]

I've also noticed the potential effect this PR has on this other one: #5072 - I can facilitate integration of those two, if needed.