PUT /collections/{collectionId}/items/{featureId} should be allowed for creation also

[philvarner]

Currently, the PUT endpoint is defined as being only for updating existing items. However, this is also a useful pattern for idempotent create of new items, and this case should be allowed.

[philvarner]

Looks like this is actually in the spec now https://docs.ogc.org/DRAFTS/20-002r1.html#put-create-feature