FormBuilderTextBox should support context menu as default

[yfakariya]

Environment

Package version: 7.8.0

Description

What you'd like to happen:

FormBuilderTextBox supports default context menu out of box.

Currently, default value for contextMenuBuilder parameter of FormBuilderTextBox is not specified, so no context menu is shown as default.
In contrast, native TextFormField specifies default implementation using AdaptiveTextSelectionToolbar.editableText.
It is great if FormBuilderTextField also support default context menu.

For your reference, the default context menu enables pasting from clipboard, selecting all inputs if there are any inputs, and cutting and copying seleted texts. I think these functions are "must-have" for UX.

[tsinis]

@yfakariya as a solution for now you can use (in your FormBuilderTextField):

contextMenuBuilder: (_, editableTextState) =>
    AdaptiveTextSelectionToolbar.editableText(
  editableTextState: editableTextState,
),

[yfakariya]

@tsinis Yes, you are right. However, my indent was that it was convinient even if we didn't specify it explicitly.

[deandreamatias]

Solved by #1212