chore(storage): add makeStorageOpts helper (#6426)

This takes out a few lines of boilerplate that will be
present in all top-level methods.

storage/client.go

@@ -162,6 +162,20 @@ func callSettings(defaults *settings, opts ...storageOption) *settings {
 	return &cs
 }
 
+// makeStorageOpts is a helper for generating a set of storageOption based on
+// idempotency, retryConfig, and userProject. All top-level client operations
+// will generally have to pass these options through the interface.
+func makeStorageOpts(isIdempotent bool, retry *retryConfig, userProject string) []storageOption {
+	opts := []storageOption{idempotent(isIdempotent)}
+	if retry != nil {
+		opts = append(opts, withRetryConfig(retry))
+	}
+	if userProject != "" {
+		opts = append(opts, withUserProject(userProject))
+	}
+	return opts
+}
+
 // storageOption is the transport-agnostic call option for the storageClient
 // interface.
 type storageOption interface {

storage/copy.go

@@ -230,13 +230,6 @@ func (c *Composer) Run(ctx context.Context) (attrs *ObjectAttrs, err error) {
 	}
 
 	isIdempotent := c.dst.conds != nil && (c.dst.conds.GenerationMatch != 0 || c.dst.conds.DoesNotExist)
-	opts := []storageOption{idempotent(isIdempotent)}
-	if c.dst.retry != nil {
-		opts = append(opts, withRetryConfig(c.dst.retry))
-	}
-	if c.dst.userProject != "" {
-		opts = append(opts, withUserProject(c.dst.userProject))
-	}
-
+	opts := makeStorageOpts(isIdempotent, c.dst.retry, c.dst.userProject)
 	return c.dst.c.tc.ComposeObject(ctx, req, opts...)
 }