Handle unions of single-item enums

[david-crespo]

In 59c40a1 we pull in changes from the following chain of PRs:

oxidecomputer/omicron#1789
oxidecomputer/dropshot#454
GREsau/schemars#152

In short, a schemars fix to put doc comments on enum variants caused dropshot to change some simple enum schemas to oneOfs of single-item enums, changing this

oxide.ts/client/Api.ts

Lines 519 to 530 in 45ead9d

	export const InstanceState = z.enum([
	"creating",
	"starting",
	"running",
	"stopping",
	"stopped",
	"rebooting",
	"migrating",
	"repairing",
	"failed",
	"destroyed",
	]);

to this

oxide.ts/client/Api.ts

Lines 520 to 531 in 59c40a1

	export const InstanceState = z.union([
	z.enum(["creating"]),
	z.enum(["starting"]),
	z.enum(["running"]),
	z.enum(["stopping"]),
	z.enum(["stopped"]),
	z.enum(["rebooting"]),
	z.enum(["migrating"]),
	z.enum(["repairing"]),
	z.enum(["failed"]),
	z.enum(["destroyed"]),
	]);

Fortunately the inferred type ends up the same, and I think in practice the runtime behavior is also the same. So we don't necessarily have to convert this back to what it was before, though it would be neater. It would be nice to pull in the newly available comments on each variant, though.

https://github.com/oxidecomputer/omicron/blob/74f3ca89af11b0ce6d9f9bd4b5bdcbeb04d1ba3e/openapi/nexus.json#L9098-L9114

[david-crespo]

Fixed by #179