Fix project manager minimum size not being large enough

[Calinou]

This caused UI elements to be cut off when the window was resized to its lowest allowed size.

• Related to Project Manager window is cut off on smaller screens #111735.

Preview

Before	After

[arkology]

I'm pretty sure some controls could be tweaked to fit UI into existing window size without increasing it.
I mean, increasing window size does not fix the root of the problem.
For example, to prevent vertical overflow we can put buttons on the right side into scroll container. I almost sure this will fix the problem.
That causes horizontal overflow? IDK, but maybe it may be title bar.

[arkology]

I've opened PR to fix vertical overflow (linked above).
Unfortunately I can not reproduce horizontal overflow, but most likely this is caused by title bar (its custom minimum size).

[KoBeWi]

I also can't reproduce the horizontal overflow. The Show in File Manager button was removed, so the problem might be solved already.