Add Bench mark for text render optimized TryGetGlyphMetricsAtOffset

[Faolan-Rad]

Description

This was me just finds Glyph Metrics when it loads and updates rather then on every TryGetGlyphMetricsAtOffset which improves performance even more

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[Faolan-Rad]

This is based off this pull request Speed up Unicode Data lookups and remove reflection

[JimBobSquarePants]

Hi @Faolan-Rad thanks for your PR.

To accept this I would have to see two things.

1. Proof that this area is a processing hotspot and that it requires extra optimization.
2. Before/After benchmark results showing the improvement from the change.

I would need some convincing to see the usefulness of this change. GlyphPositioningCollection.TryGetGlyphMetricsAtOffset(...) is only called during line breaking which involves a sequential run against the codepoints within the string. This means that a given offset is only requested one time which means any cache lookup will always return false.

[JimBobSquarePants]

Sorry @Faolan-Rad This was auto closed when I merged the base branch. If you still feel like it is required please repoint the PR at the main branch.