feat: migrate policy APIs to Connect RPC

internal/api/v1beta1connect/errors.go

@@ -46,4 +46,8 @@ var (
 	ErrBillingProviderNotSupported = errors.New("provider not supported")
 	ErrInsufficientCredits         = errors.New("insufficient credits")
 	ErrAlreadyApplied              = errors.New("credits already applied")
+	ErrInvalidRoleID               = errors.New("role id is invalid")
+	ErrNamespaceSplitNotation      = errors.New("subject/object should be provided as 'namespace:uuid'")
+	ErrPolicyNotFound              = errors.New("policy doesn't exist")
+	ErrProjectNotFound             = errors.New("project doesn't exist")
 )