feat: listbox properties spec

[T-Wizard]

Start of ListboxProperties spec

Motivation

Requirements checklist

• Api specification
  • Ran yarn spec
    • No changes OR API changes has been formally approved
• Unit/Component test coverage
• Correct PR title for the changes (fix, chore, feat)

When build and tests have passed:

• Add code reviewers, for example @qlik-oss/nebula-core

[Caele]

Should we really put this here? Think it will just be more confusing if we mix this into the other Nebula stuff. Could instead reference a different api, either a nebula-list-box or the sn-listbox one.

[veinfors]

Should we really put this here? Think it will just be more confusing if we mix this into the other Nebula stuff. Could instead reference a different api, either a nebula-list-box or the sn-listbox one.

Sure, can agree that it could be nice to have it as a separate Api. We have already discussed it a little bit back and forth, but let's have a little talk about it tomorrow and decide what to do.

[T-Wizard]

Should we really put this here? Think it will just be more confusing if we mix this into the other Nebula stuff. Could instead reference a different api, either a nebula-list-box or the sn-listbox one.

If we split it to a different api, I don't know how to reference it in a way that also get the types for the generated typescript definition.

@Caele: except that it it something like #1245 you want instead?
(if not I need more info about what you want)

[Caele]

LGTM
Don't really know how we "solve" typings for TS, but I think this is a safer approach to get us started.