Drop useless options from flatpak info

The --app and --runtime options are not really useful
for flatpak info, since you need to specify a full ID
anyway, and it is highly unlikely that you will have
ID clashes between apps and runtimes. Also, the options
are documented in a confusing way.
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Internal Server Error - Gitea: Git with a cup of tea
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Gitea Version: 1.28.0+dev-477-g8b6ad49a5f