RFR: 8245053: Keyboard doesn't show when TextInputControl has focus [v6]

[Abhinay Agarwal]

> In Android, TextInputControls (TextField and TextArea) are responsible for showing and hiding software keyboard.
> Currently, a focus listener is attached to these controls and is used to toggle the visibility of keyboard. This
> condition fails in cases where the control already has focus but the keyboard is not visible.  Ideally, the keyboard
> should be shown again when the user taps on the TextInputControl.
> This PR adds an event handler for `MouseEvent.MOUSE_CLICKED` event and shows the keyboard  if the TextInput control is
> both editable and focused.

Abhinay Agarwal has refreshed the contents of this pull request, and previous commits have been removed. The
incremental views will show differences compared to the previous content of the PR. The pull request contains one new
commit since the last revision:

  Show keyboard on mouse event. Focus change listener should be responsible for hiding the keyboard only.

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/219/files
  - new: https://git.openjdk.java.net/jfx/pull/219/files/0aa79029..b13c44b3

Webrevs:
 - full: https://webrevs.openjdk.java.net/jfx/219/webrev.05
 - incr: https://webrevs.openjdk.java.net/jfx/219/webrev.04-05

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/219.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/219/head:pull/219

PR: https://git.openjdk.java.net/jfx/pull/219