[app] unify preferences.xml from build flavors

previously basic and main source set had a different preferences.xml which we needed to keep in sync manually. When we forgot to do this, this caused crash bugs. Hence, this commit unifies both files into one and uses a boolean resource to hide full preferences in basic flavor.
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Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f