feat(12.2-02): add the fileupload field with deferred uploads committed on save

- type: fileupload compiles the D-08 keys and binds to the model's attach.Relation at boot
- X-Session-Key (cabana.SessionKeyHeader) carries the form session key; RecordInput.SessionKey
- GET and POST .../{id}/files/{field}: list with pending uploads, multipart upload into attach.Store
- the create and update save attaches the session's pending files in its transaction
- swagger2openapi folds formData parameters into a multipart requestBody
- admin OpenAPI, TS types, conformance cases, README and forms docs

modules/cabana/registry.go

@@ -93,6 +93,9 @@ func compileRegistry(items []controllerRef) (*Registry, error) {
 		if err := BindWritableFields(compiled); err != nil {
 			return nil, err
 		}
+		if err := compileFileFields(item.plugin.ID(), compiled); err != nil {
+			return nil, err
+		}
 		if err := compileExtension(item.plugin.ID(), compiled, fsys.AdminFS()); err != nil {
 			return nil, err
 		}