Text/glyph caching

[simbleau]

Recalculating bounding boxes of vello text is not efficient to compute and should be updated only when the text itself changes.

Potential optimizations:

• We can heavily rely on component hooks in bevy to determine if style/text change to re-calculate AABB size, rather than computing every update.
• We can rely on potential APIs within parley or vello to use glyph caching.