fix(graphics): Large Text segments render properly by breaking them into smaller pieces

[eonarheim]

===:clipboard: PR Checklist :clipboard:===

• 📌 issue exists in github for these changes
• 🔬 existing tests still pass
• 🙈 code conforms to the style guide
• 📐 new tests written and passing / old tests updated with new scenario(s)
• 📄 changelog entry added (or not needed)

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Closes #2290

This PR adds some additional logic into the text rendering code of Font that breaks the underlying text raster into separate < 4k sized chunks that will work on mobile platforms.

Changes:

• Adds a TextureLoader.delete(imageSource) method for cleaning up old GPU textures