Testing result of Pull Request #14919: Add a per-state stroke model for Net11 editable-control borders

# Testing Results
Performed re-validation of the TextBoxBase modern field stroke implementation (TextBox, MaskedTextBox, and RichTextBox) under VisualStylesMode.Net11 for GH PR: https://github.com/dotnet/winforms/pull/14919 after the latest updates

State transitions behave as expected:

- Rest state displays a distinct Hover state when the pointer moves over the control.
- Focused state displays the accent-colored bottom edge as designed.
- ReadOnly controls do not enter a Hover visual state.
- Disabled controls remain visually unchanged regardless of mouse interaction.
- State precedence appears consistent with the documented model:
Disabled > Focused > ReadOnly > Hover > Rest.

Previously reported design feedback items have been addressed and the overall visual appearance is now more consistent across states.
But have 3 opening issues, related to BorderStyle-specific state rendering.

# Design Feedback
## Feedback 1: Rest State Bottom Edge Could Better Align with the Focus-State Geometry - Resolved

## Feedback 2: Focus Bottom Edge Appears Slightly Too Thick - Resolved

## Feedback 3: Hover State Reduces the Apparent Editable Area - Resolved

## Feedback 4: ReadOnly and Disabled States Introduce a Visible Inner Border - Resolved
Custom BackColor setting, except disabled RichTextBox control(It has issue here: https://github.com/dotnet/winforms/issues/15053):

Setting Padding to 20:

## Issue 1: Both design time and runtime , no border existing when `BolderStyle `is `FixedSingle `for TextBox/MaskedTextBox/RichTextBox controls - partially fixed, for RichTextBox with BorderStyle = none, it should haven't border --- Filed a separate issue: https://github.com/dotnet/winforms/issues/15055
VisualStylesMode = NET11:

VisualStylesMode = Classic:

## Issue 2: FixedSingle BorderStyle Applies Accent Color to the Entire Border
**Observed Behavior**
When the control receives focus:
• The accent color is applied to the entire border (top, left, right, and bottom).
• The control displays a full accent-colored outline.

**Affect controls:** TextBox/MaskedTextBox/RichTextBox
**Impact**
This creates an inconsistent appearance across BorderStyle variants and differs from the intended TextBoxBase focus-state design, where focus is indicated by an accent-colored bottom edge rather than a full border outline

## Issue 3: Hover Visual State Is Missing for FixedSingle and None BorderStyles
**Observed Behavior**
When the pointer moves over the control:
• BorderStyle = Fixed3D
○ A visible Hover state is displayed.
• BorderStyle = FixedSingle
○ No visible difference between Rest and Hover states.
• BorderStyle = None
○ No visible difference between Rest and Hover states.

****Affect controls:** TextBox/MaskedTextBox/RichTextBox
Impact**
The same control exhibits different state behavior depending on BorderStyle. As a result, users receive Hover feedback with Fixed3D, but no Hover feedback with FixedSingle or None, leading to inconsistent interaction behavior.