Shows and hides keyboard when scrolling the app drawer

[hayribakici]

This PR is a UX enhancement when scrolling through the app drawer.

If the show keyboard option is set, it will minimize the keyboard once users start scrolling down the app drawer. Vice versa, it displays the keyboard when the user is scrolling up again.

Show keyboard when scrolling up

In order to be smooth, the MainActivity's android:windowSoftInputMode had to be set to adjustNothing. This however conflicts with PR #143 , since it would cover the search field if it set to the bottom of the screen. There are fixes for this as seen in an official android guide.

[hayribakici]

This PR is now outdated. As mentionend in the description, therefore reverting to draft. I propably won't be able to continue/fix the issue, and I would be grateful, if someone would pick this up.

[TobiTenno]

we're still talking over this, i don't know if it's quite gonna fit, especially with the search moving to the bottom, optionally