Resizing windows in MacOS sucks

- [*] I have checked that a similar [feature request](https://github.com/Genymobile/scrcpy/issues?q=is%3Aopen+is%3Aissue+label%3A%22feature+request%22) does not already exist.

**Is your feature request related to a problem? Please describe.**
Ever since Android started adding gestures that affect the screen edges, scrcpy has become very difficult to use due to accidentally resizing the window constantly.

**Describe the solution you'd like**
Some way to lock the window dimensions would be nice.

Start by locating scrcpy's macOS window-resizing behavior and determine where a window-dimension lock could be handled. Done means users can lock the window dimensions so edge gestures no longer accidentally resize it.

Written by the indexing model from the issue text.