USWDS-3479 Combo Box Subsequent Selection

[wbyoko]

Current implementation in Federalist

Description

closes #3479

This updates the ux of selecting an item after an item has been selected.

New and Updated Test Cases

• should emit change events when resetting input values when an incomplete item is submitted through enter
• should not show the list when clicking a disabled toggle button
• should show the list when clicking the input once the component has been enabled
• should display the full list and focus the selected item when the input is pristine (after fresh selection)
• should display the filtered list when the input is dirty (characters inputted)
• should show a clear button when the input has a selected value present
• should update the filter and begin filtering once a pristine input value is changed
• should show the list by clicking the toggle button
• should toggle the list and close by clicking when clicking the toggle button twice
• should reset input values when an incomplete item is remaining on blur
• should reset input values when an incomplete item is submitted through enter
• should not allow enter to perform default action when the list is hidden
• should close the list and reset input value when escape is performed while the list is open
• should reset the input value when a complete selection is left on blur from the input element
• should select the focused list item in the list when pressing tab on a focused item
• should not select the focused list item in the list when blurring component from a focused item

Additional information - Screenshot images

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• Follow the 18F Front End Coding Style Guide and Accessibility Guide.
• Run npm test and make sure the tests for the files you have changed have passed.
• Run your code through HTML_CodeSniffer and make sure it’s error free.
• Title your pull request using this format: [Website] - [UI component]: Brief statement describing what this pull request solves.

[thisisdano]

This is a pretty extensive set of improvements! I have a couple questions related to this work, but I'm inclined to merge this now, and do any additional polish in a follow-up.