[Impeller] Reduce hashing and std::shared_ptr operations during text workloads. #133201
Description
Each FontGlyphPair that we render will be hashed twice, once to deduplicate and collect all glyphs for a frame, and another time in the text contents. The hash computation itself is adding up. Additionall, the Typeface shared_ptr has a lot of ops on it too. We should find a way to reduce the amount of hashing.
