Rework data binding to use generic types

[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?

With #5377 landed, there is only the code generation for data binding left. As there is quite a lot of code duplication between the binding types, this would be a wise place to apply generics and decrease our reliance on code generation. This should improve developer ergonomics and make the code easier to understand.

Is it possible to construct a solution with the existing API?

I think so. It might be possible to rewrite some internal types to use generics without impacting the public API but I think a nice change for v3.0.0 further down the line would be to have a public generic API for bindings (far into the future but anyway).

Describe the solution you'd like to see.

Clean up data binding using generics to try and remove code generation as much as possible.

[andydotxyz]

We need to pay attention to the possible need for comparators as well - the custom types in tree/list need to be able to do change detection which we are falling short on at the moment.

[Jacalz]

Indeed. The cmp package may be useful for that: https://pkg.go.dev/cmp