Parent issue: #16311

hb-subset provides functionality to pull glyphs out of a font and create a new, smaller font file. We should update the engine build recipes to add a target for hb-subset if one doesn't already exist, build it, and upload it to cloud storage for consumption by the framework tooling.

Once this is done, we can update the tooling to consume this package and use it to shrink down the Material and Cupertino icon fonts at build time.

/cc @willlarche