Add more window management actions

[reibitto]

Some ideas for additional actions:

• Minimize all windows for a particular monitor
• "Almost maximize" like in Rectangle
• Refactor GlobalAction to be an ADT, and then we can have separate configs for each action. That would allow us to write 1 "transform window" GlobalAction that takes in config params to take care of any kind of window transformation. Like: top left, top right, bottom left, bottom right, first third, second third, etc. Refer to Rectangle's options for what I mean:

Feel free to add suggestions for anything that's missing.