Add set / unset actions for maximize-column (or expose its state via IPC)

[pundemia-dev]

maximize-column is currently only available as a toggle action.

This makes it difficult to write reliable automation scripts using niri msg event-stream. For example, I have a small script that automatically switches between a terminal and Zed in a tabbed column:

• when Zed is focused, the column should be maximized;
• when the terminal is focused, the column should return to its normal width.

With only a toggle action, there is no reliable source of truth. The script can easily get out of sync if:

• the user manually presses the maximize-column keybinding;

• another script calls maximize-column;

• another window joins the tabbed column or focus changes unexpectedly.

set-column-display already provides idempotent actions (set-column-display normal/tabbed), which makes scripting straightforward.

It would be great to have something similar for column maximization, for example:

• set-column-maximized
• unset-column-maximized

or

• set-column-maximized true|false

Alternatively, exposing the current maximized state through the IPC (e.g. in focused-window, windows, or another command) would also solve the problem.

This would make automation much more robust without affecting existing behavior.

[Sempyos]

Will note you can monitor the existing size of the window and then use that to see if it's maximized or not

[heyoeyo]

Related: #338, #1843

It would also be nice if maximize-column worked on 100% width windows, since it's currently very easy to break from scripts due to the invisible state, eg. in a terminal:

niri msg action set-window-width 100%
niri msg action maximize-column  # Invisible state
# ...
niri msg action maximize-column  # we're stuck

[YaLTeR]

Set actions for those sound reasonable yeah