RFR: 8341670: [Text, TextFlow] Public API for Text Layout Info [v7]

[Andy Goryachev]

> The RichTextArea control ([JDK-8301121](https://bugs.openjdk.org/browse/JDK-8301121)), or any custom control that needs non-trivial navigation within complex or wrapped text needs a public API to get information about text layout.
> 
> This change fixes the missing functionality by adding a new public method to the `Text` and `TextFlow` classes.:
> 
> 
>     /**
>      * Obtains the snapshot of the current text layout information.
>      * @return the layout information
>      * @since 24
>      */
>     public final LayoutInfo getLayoutInfo()
> 
> 
> The `LayoutInfo` provides a view into the text layout within `Text`/`TextFlow` nodes such as:
> 
> - text lines: offsets and bounds
> - overall layout bounds
> - text selection geometry
> - strike-through geometry
> - underline geometry
> - caret information
> 
> This PR also adds the missing `strikeThroughShape()` method to complement existing `underlineShape()` and `rangeShape()` for consistency sake:
> 
> 
>     /**
>      * Returns the shape for the strike-through in local coordinates.
>      *
>      * @param start the beginning character index for the range
>      * @param end the end character index (non-inclusive) for the range
>      * @return an array of {@code PathElement} which can be used to create a {@code Shape}
>      * @since 24
>      */
>     public final PathElement[] strikeThroughShape(int start, int end)
> 
> 
> ## WARNING
> 
> Presently, information obtained via certain Text/TextField methods is incorrect with non-zero padding and borders, see [JDK-8341438](https://bugs.openjdk.org/browse/JDK-8341438).
> 
> It is not clear whether this PR should correct the computation at least for the new APIs and keep the existing APIs as is to be fixed later, or if the fix should be applied to both sets of APIs at the same time.

Andy Goryachev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 13 additional commits since the last revision:

 - Merge remote-tracking branch 'origin/master' into ag.text.layout.api
 - remove line spacing
 - tests
 - whitespace
 - caret info
 - text line info
 - Merge remote-tracking branch 'origin/master' into ag.text.layout.api
 - convert to wrapper
 - clarify
 - javadoc
 - ... and 3 more: https://git.openjdk.org/jfx/compare/94382d87...5ab4f47a

-------------

Changes:
  - all: https://git.openjdk.org/jfx/pull/1596/files
  - new: https://git.openjdk.org/jfx/pull/1596/files/c2e26d5e..5ab4f47a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1596&range=06
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1596&range=05-06

  Stats: 319 lines in 14 files changed: 271 ins; 12 del; 36 mod
  Patch: https://git.openjdk.org/jfx/pull/1596.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1596/head:pull/1596

PR: https://git.openjdk.org/jfx/pull/1596