Redesign the tab for sending data

[Jacalz]

Checklist

• I have searched the issue tracker for open issues that relate to the same feature, before opening a new one.
• This issue only relates to a single feature. I will open new issues for any other features.

Is your feature request related to a problem?

The send tab has more or less been the same for many years now and I have never really liked how there is a very long button (looks even worse in large window sizes) and that there then is a dialog that pops up to display choices for selecting what to send. However, I have never really managed to come up with a better idea.

Describe the solution you'd like to see.

We need some sort of way to more cleanly present the options for sending files, folders and text without looking bad for large window sizes and so on. With support for dropping files onto the application coming in v3.5.0, maybe we can even make it show that more clearly as well?

[Jacalz]

I'm not entirely sure if this is better or worse. The option for a custom code definitely doesn't make sense there though.

[Jacalz]

Another idea (that I probably prefer over the one above):

With the entry for custom codes inline it almost looks quite nice:

[Jacalz]

Some inspiration from the Google image drop page:

[Jacalz]

This is how LocalSend does it:

[Jacalz]

Implemented in #172