Fix: station rating tooltip outline

[WenSimEHRP]

Motivation / Problem

The current station rating tooltip uses four GfxDrawLine, which causes problems with larger interface sizes.

1x	4x

Description

Reference:

https://github.com/citymania-org/cmclient/blob/02d6792570e1ff228d15ba968af9f36e04d23a68/src/citymania/cm_tooltips.cpp#L141-L144

Use this piece of code from cmclient.

There isn't a default gray window fill, so instead of using single rect to overlap the other rect (vanilla tooltips), use four rects.

1x	2x	4x

Limitations

None that I can think of.

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR touches english.txt or translations? Check the guidelines
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, game_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker

[JGRennison]

Thanks