This change ensures that the Material text selection toolbar correctly positions its items (including the overflow button) according to the current `TextDirection` (LTR or RTL).

Previously, the layout logic did not account for text direction, leading to incorrect placement of items in RTL layouts.

The `_TextSelectionToolbarItemsLayout` and its corresponding `_RenderTextSelectionToolbarItemsLayout` now explicitly take a `textDirection` parameter. The `_placeChildren` method in the render object has been updated to arrange items from right-to-left when in an RTL context.

…ght-to-left in RTL

This commit introduces tests to verify that:
- Items in `TextSelectionToolbar` are correctly ordered from right-to-left when the `textDirection` is `TextDirection.rtl`.
- The overflow menu in `TextSelectionToolbar` functions as expected in RTL mode, correctly displaying and hiding overflowed items.

…ght-to-left in RTL

This commit introduces tests to verify that:
- Items in `TextSelectionToolbar` are correctly ordered from right-to-left when the `textDirection` is `TextDirection.rtl`.
- The overflow menu in `TextSelectionToolbar` functions as expected in RTL mode, correctly displaying and hiding overflowed items.

…l' into fix-text-selection-toolbar-in-rtl

The previous test for right-to-left (RTL) item ordering in `TextSelectionToolbar` incorrectly assumed items would be perfectly adjacent. This commit revises the test to accurately verify that items are positioned to the left of their preceding items in RTL, allowing for potential spacing or visual separation between them.

The test now:
- Adds `Text` widgets as children to `TestBox` for easier identification and position retrieval.
- Verifies that `next.right` is less than or equal to `current.left` for each pair of items in RTL.
- Additionally confirms the visual right-to-left order by comparing the sorted list of right edges with the actual list.

This commit refactors the `_placeChildrenHorizontally` method in `TextSelectionToolbar` for improved clarity and efficiency.

The changes include:
- Renaming variables for better readability (e.g., `paintedContentItems` to `contentItems`, `totalHorizontalWidth` to `totalWidth`).
- Simplifying the logic for collecting and positioning child items by iterating directly over children using `visitChildren`.
- Using a boolean `showNavButton` derived from `_lastIndexThatFits` to determine if the navigation button should be painted, instead of a separate `navButtonIsPainted` flag.

This commit refactors the `_placeChildrenVertically` method within the `_TextSelectionToolbarContentLayout` class of the Material text selection toolbar.

The changes include:
- Using `visitChildren` for iterating over child render objects, replacing the manual linked-list traversal.
- Renaming `maxItemWidth` to `maxWidth` for clarity.
- Removing the unused `nextSize` variable.
- Simplifying the logic for handling the navigation button.

These changes improve the readability and maintainability of the vertical layout logic for the overflow menu in the Material text selection toolbar.

This commit refactors the logic within the `TextSelectionToolbar`'s `performLayout` method.
Specifically, it streamlines the condition for determining whether a child should be painted. Instead of checking `_shouldPaintChild` and then setting `shouldPaint` to true or false, it now directly checks `!_shouldPaintChild` to set `shouldPaint` to false, with an `else` block to set it to true. This improves readability without changing the underlying behavior.