Show all options in combobox when opening

[dannify]

TBD

Investigate if this is feasible

Points to consider:

• expected behavior when filtering is controlled (e.g. items + inputValue controlled), we would want to retain the input value but need to get the unfiltered list
  • additional wrinkle to this is async filtering (how would a user return the full list of items without changing input value? should they? perhaps expectation would be that user provides a default list? could we save a default/initial list internally)