revamp status quo section for harmonic synthesis

[nikomatsakis]

This is an attempt to create a coherent "status quo" section that both

• highlights what we see as the biggest problems we see for async rust (details not yet written!)
• and creates a small set of narratives, based on our projects, that show those problems in action

I am realizing as I go that this exercise is uncovering some gaps in my knowledge. For example, I don't have a good summary of what it's like to author an embedded crate.

I'd really love to hear from folks about

• "biggest problems" or themes that I've overlooked
• thoughts on the set of narratives -- are there themes that we are not able to cover because of the choice of narratives that should be added?

One thing I thought might be missing, for example, is someone shooting for a "ruby on rails"-like experience, e.g. by using rocket or tide or something like that. What's that like? Another theme might be C++ interop (cc @pcwalton), although the story about 'monster mesh' covers the DMA angle which is kind of the "need a non-cancellable future" angle.