Merge client configuration files

[jwrober]

Is your feature request related to a problem? Please describe. I think we should merge all of the client configuration files into one. Right now we have

~/.config/freeciv21-client.ini ~/.local/share/freeciv21/freeciv-client-rc-3.0

Describe the solution you'd like Rename ~/.local/share/freeciv21/freeciv-client-rc-3.0 to ~/.local/share/freeciv21/freeciv21-client-rc and then merge the contents of ~/.config/freeciv21-client.ini into ~/.local/share/freeciv21/freeciv21-client-rc

Describe alternatives you've considered None

Additional context N/A

[lmoureaux]

The use of .config is conforming to the XDG spec, .local should not be used for configuration files.

[jwrober]

Might think about using KConfig as a more robust way to manage client configuration

• https://invent.kde.org/frameworks/kconfig
• https://invent.kde.org/frameworks/kconfigwidgets

[lmoureaux]

KConfig docs:

• https://develop.kde.org/docs/use/configuration/introduction/
• https://api.kde.org/frameworks/kconfig/html/index.html

[jwrober]

Related: #568

[jwrober]

https://develop.kde.org/docs/features/configuration/introduction/

[jwrober]

As I continue to think about this issue... I want to take advantage of the big move to Qt6 to go to kconfig. I also want to move all "config" to common so other apps like the modpack-installer or even ruledit can use the same themes or other common themes.