feat: add new ErrNoSpaceLeftOnDevice API error for ENOSPC errors

Add a new non-AWS error ErrNoSpaceLeftOnDevice (HTTP 507 Insufficient
Storage) to s3err. Update all call sites in the posix backend that
could return ENOSPC and return the new error when the underlying
filesystem has no space remaining.

Fixes #2093

s3err/s3err.go

@@ -199,6 +199,7 @@ const (
 	ErrQuotaExceeded
 	ErrVersioningNotConfigured
 	ErrACLsDisabled
+	ErrNoSpaceLeftOnDevice
 
 	// Admin api errors
 	ErrAdminAccessDenied
@@ -904,6 +905,11 @@ var errorCodeResponse = map[ErrorCode]APIError{
 		Description:    "Access control lists are disabled at the gateway level",
 		HTTPStatusCode: http.StatusBadRequest,
 	},
+	ErrNoSpaceLeftOnDevice: {
+		Code:           "InsufficientStorage",
+		Description:    "No space left on device.",
+		HTTPStatusCode: http.StatusInsufficientStorage,
+	},
 
 	// Admin api errors
 	ErrAdminAccessDenied: {