feat: add additional functionality to listbox base

[scomea]

Description

• add and implement autofocus and disabled props to listbox, these were found to needed to implement Select component
• exposed some utility static functions. These are used by the Select component when it wants to manipulate selected items when the listbox is not actually instanciated.

Motivation & context

Towards a working select component

Issue type checklist

• Chore: A change that does not impact distributed packages.
• Bug fix: A change that fixes an issue, link to the issue above.
• New feature: A change that adds functionality.

Is this a breaking change?

• This change causes current functionality to break.

Process & policy checklist

• I have added tests for my changes.
• I have tested my changes.
• I have updated the project documentation to reflect my changes.
• I have read the CONTRIBUTING documentation and followed the standards for this project.

[codeclimate]

Code Climate has analyzed commit aed8183 and detected 5 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	1
Duplication	4

The test coverage on the diff in this pull request is 76.4% (50% is the threshold).

This pull request will bring the total coverage in the repository to 88.3% (0.0% change).

View more on Code Climate.