Add rotated rectangle draw and fill methods

[BillMerryman]

These methods implement the ability to draw and fill rectangles rotated by a given angle in degrees.

[BillMerryman]

@ladyada for review.

[ladyada]

thanks! please also add some example to test this code, maybe displaying rotating rectangles - so we can easily verify functionality on platforms/displays :)

[Copilot]

Pull Request Overview

This PR adds support for drawing rotated rectangles to the Adafruit GFX library. The implementation includes functions to draw outlined rotated rectangles, filled rotated rectangles, and a helper function to rotate points around an origin.

• Adds drawRotatedRectangle and fillRotatedRectangle methods for rendering rotated rectangles
• Implements a rotatePoint helper function for coordinate rotation
• Uses trigonometric functions to rotate rectangle corners and existing drawing primitives (lines and triangles) for rendering

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
Adafruit_GFX.h	Adds method declarations for the three new rotated rectangle functions
Adafruit_GFX.cpp	Implements the rotated rectangle drawing logic with supporting rotation math

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[BillMerryman]

Wasn't sure where you wanted an example, so I placed one in the 'examples' directory in a directory called 'RotatedRectangleTest'. Commented the display-specific code.

[BillMerryman]

@ladyada for review.