add webauthn crud endpoints

added some simple validation to the delete endpoint for sanity, but
generally my assumption is that more validation will happen on the admin
side.

noteably im not checking whether the credentials are duplicated, nor is
there a uniqueness constraint in the database - I'm not sure if the
credential blob will always reliably be equivalent, and I believe the
browser should hopefully take care of dupes.

app/webauthn/webauthn_schema.py

@@ -0,0 +1,23 @@
+post_create_webauthn_credential_schema = {
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "description": "POST webauthn_credential schema",
+    "type": "object",
+    "properties": {
+        "name": {"type": "string"},
+        "credential_data": {"type": "string"},
+        "registration_response": {"type": "string"},
+    },
+    "required": ["name", "credential_data", "registration_response"],
+    "additionalProperties": False
+}
+
+post_update_webauthn_credential_schema = {
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "description": "POST update webauthn_credential schema",
+    "type": "object",
+    "properties": {
+        "name": {"type": "string"},
+    },
+    "required": ["name"],
+    "additionalProperties": False
+}