Update the used Flutter version to 3.16.0 and all Flutter packages to
their latest version.
This commit also fixes all of the newly added analysis options and the
layout changes introduced with the new Flutter version (e.g. we have to
set the "tabAlignment" property in the "TabBar" widget).
This commit adds links to the privacy policy and terms & conditions to
the distributed apps as it is required for the in-app purchase
submission in the Apple App Store.
This commit also updates the terms & conditions to include a specify
section when FeedDeck is used via the Apple App Store, Google Play Store
or the Windows Store.
This commit adds a "Get Started" guide for the mobile and desktop
version of FeedDeck. The guide describes the basic concepts and settings
of the app to make it easier to get started with the FeedDeck.
This is also used for the review process in the different app stores to
make it easier to get the app approved.
The settings page now contains an info section, which is used to show
the current app version via the "package_info_plus" package, the link to
our website, the link to our GitHub repository and the link to our X
account.
