Nextlove should support `.optional()` on formData

[seveibar]

We currently can't do z.object({ ... }).optional() with nextlove's formData, it will always fail to parse, so instead we do a hack where we do z.union([z.any(), z.object({ ... })]), let's fix this!

          yea this is imo a nextlove bug, we should be able to do `.optional()`

Originally posted by @seveibar in https://github.com/seamapi/seam-connect/pull/4685#discussion_r1371085647