Add list of save files to save window

[ianleeder]

Reasoning

When playing multiple sessions, I forget the name of the existing save file. I figured it might be nice to copy the list of save files like on the Host window, and use that on the Save window.

I copied just about everything from ServerBrowser.cs DrawHost().

Example Host window

Existing MP Save window

New MP Save window

[ianleeder]

Hmm, just realised I need to check the button layouts when dev isn't enabled. I suspect the OK button will be off-centre 🤢

[maxsupermanhd]

Yes, we NEED IT! Thanks!

[SaberShip]

Well done! I had considered doing this as well but never found the time! Glad to see this nice QOL improvement.

[ianleeder]

Ok I've adjusted very slightly.

• Made the window a little narrower, it didn't need to be that wide.
• Fixed bug where the dev replay button wasn't conditional
• Centered the Save button if no dev button is shown

Ready for review/merge