want ability to pin projects

[iliana]

On our internal silos we have lots of per-user projects. I'd like the ability to pin the projects I care about to the top of the list. The pins should be modeled as a user preference of some kind, not as a silo-wide setting.

[david-crespo]

Could do it in localStorage but then it wouldn't be shared across devices. API-side is better oxidecomputer/omicron#9930