[Combobox] Support editing custom single-select values, rather than re-entering new values

[mpayson]

Description

In order to edit a custom value in a combobox, users currently have to deselect their custom value, then enter a new value, which is respectably challenging. It'd be great if users could edit existing values

Acceptance Criteria

Users can edit existing custom combobox values that they entered, and ideally edit combobox options as well

Relevant Info

No response

Which Component

calcite-combobox

Example Use Case

We have a control in our app that allows users to select a date format, or enter a custom date format. If a user accidentally types MM/DD/yyyy hh:m.ss for a custom format instead of MM/DD/yyyy hh:mm.ss, they have to re-renter the whole value, rather than inserting an m. It's also hard to copy the current combobox value to avoid having to retype. We have a similar use case for character encodings

Priority impact

p4 - not time sensitive

Esri team

ArcGIS Online

[mpayson]

Maybe part of #6720?

[ashetland]

While we explore what this interaction would entail, would the ability to delete items also be useful here? This of course brings up further questions like can the user only delete items they've added? How are these item differentiated?

[mpayson]

For our use case, I'm not sure the items need to be deleted, or even if the custom values need to be added to the list. Here are some similar interactions in other libraries

• https://learn.microsoft.com/en-us/fluent-ui/web-components/components/combobox
• https://mui.com/material-ui/react-autocomplete/#search-input