GUI: Fix font change

[gzotti]

Description

StelApp is the only element which ever accepts a font change.
Currently, several StelModules have their own fonts which may get initialized at startup, but then only size was changed.

When switching font, the font change should become effective immediately, not only after relaunch.

This is a first step to hopefully fix the font issues which appeared with Skycultures demands.

This branch should be used to

• fix issues with missing glyphs (Bab. SCs: add cuneiform in "Native" tags #4339) and
• fix bounding box issues (Arabic Al-Sufi lunar mansions' names are shifted with respect to their sections #4493).

Screenshots (if appropriate):

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• This change requires a documentation update
• Housekeeping

How Has This Been Tested?

Test Configuration:

• Operating system: Windows 11
• Graphics Card: irrelevant

Checklist:

• My code follows the code style of this project.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (header file)
• I have updated the respective chapter in the Stellarium User Guide
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[github-actions]

Hello @gzotti!

Thank you for the suggested improvement.

[github-actions]

Great PR! Please pay attention to the following items before merging:

Files matching src/**/*.cpp:

• Are possibly unused includes removed?

This is an automatically generated QA checklist based on modified files.

[gzotti]

(git messup with upper/lowercase branch name. Closing this, coming back in other PR...)

[github-actions]

Hello @gzotti!

Please check the fresh version (development snapshot) of Stellarium:
https://github.com/Stellarium/stellarium-data/releases/tag/weekly-snapshot

[github-actions]

Hello @gzotti!

Please check the latest stable version of Stellarium:
https://github.com/Stellarium/stellarium/releases/latest