[jfx17] RFR: 8270314: TreeTableCell: inconsistent naming for tableRow and tableColumn property methods

[Kevin Rushforth]

In the `TreeTableCell` class there is a mismatch between name of the following property method vs the getter:


    public final ReadOnlyObjectProperty<TreeTableRow<S>> tableRowProperty()
    public final TreeTableRow<S> getTreeTableRow()


The get method has "Tree" in the name while the property method does not.

By contrast, the corresponding methods for column are self-consistent, and are named without "Tree" in the name:


    public final ReadOnlyObjectProperty<TreeTableColumn<S,​T>> tableColumnProperty()
    public final TreeTableColumn<S,​T> getTableColumn()


The solution is to effectively change `getTreeTableRow()` to `getTableRow()`. In order to preserve source and binary compatibility, the method is copied rather than renamed. The existing `getTreeTableRow()` method is deprecated (not for removal).

Additionally, the docs for each property is on a private property field that *does* have tree in the name, which results in no docs being generated for either the `tableRow` or `tableColumn` property.

Finally, there is a problem with the implementation of the `tableRowProperty()` method in that it returns the writable property by mistake rather than the read-only property that is specified by the method's return type.

In summary, the following changes are made to `TreeTableCell`:

1. Deprecate the `getTreeTableRow` method.
2. Add a `getTableRow` method.
3. Rename the (private) property object fields from `treeTableRow` and `treeTableColumn` to `tableRow` and `tableColumn`, including the name of the bean, so that they match the public property method names. This will allow API docs to be generated.
4. Change the implementation of the tableRowProperty() method to return a read-only property.

In addition to changing the existing implementation and tests to call the new `getTableRow` method instead of the now-deprecated `getTreeTableRow` method, I added unit tests to validate changes 3 and 4.

NOTE: this is targeted to `jfx17`.

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Commit messages:
 - 8270314: TreeTableCell: inconsistent naming for tableRow and tableColumn property methods

Changes: https://git.openjdk.java.net/jfx/pull/575/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=575&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8270314
  Stats: 68 lines in 5 files changed: 36 ins; 0 del; 32 mod
  Patch: https://git.openjdk.java.net/jfx/pull/575.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/575/head:pull/575

PR: https://git.openjdk.java.net/jfx/pull/575