New example for InputChip that demonstrate how to create/delete them based on user text inputs.

The sample application shows a custom text area where user can enter text. After the user has typed and hits Enter the text will be replaced with an InputChip that contains that text. Is it possible to continue typing and add more chips in this way. All of them will be placed in a scrollable horizontal row. Also is it possible to have suggestion displayed below the text input field in case the typed text match some of the available suggestions.

Issue I'm trying to solve:

• Example of InputChips being generated from user's input. #128247

Code structure:

The example app is composed of 2 main components that find places inside MainScreen:

• ChipsInput
• ListView

ChipsInput emulates a TextField where you can enter text. This text field accepts also a list of values of generic type T (Topping in my example), that gets rendered as InputChip inside the text field, before the text inserted by the user. This widgets is basically an InputDecorator widget that implements TextInputClient to get TextEditingValue events from the user keyboard. At the end of the input field there is another component, the TextCursor, that is displayed just when the user give the focus to the field and emulates the carrets that TextField has.

There are also some available callbacks that the user can use to capture events in the ChipsInput field like: onChanged, onChipTapped, onSubmitted and onTextChanged. This last callback is used to build a list of suggestion that will be placed just below the ChipsInput field inside the ListView.

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
• I signed the [CLA].
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is [test-exempt].
• All existing and new tests are passing.