Allow upload tasks to pass concurrency and default to DEFAULT_ACTION_CONCURRENCY = 4

### On which framework/platform would you like to see this feature implemented?

React

### Which UI component is this feature-request for?

Storage

### Please describe your feature-request in detail.

Using the storage file browser the upload action can't be configured with a concurrency to upload files. This seems to be hardcoded with DEFAULT_ACTION_CONCURRENCY = 4.

### Please describe a solution you'd like.

_No response_

### We love contributors! Is this something you'd be interested in working on?

- [ ] 👋 I may be able to implement this feature request.
- [ ] ⚠️ This feature might incur a breaking change.

No file or test is named in the issue. Start by locating the Storage upload action and DEFAULT_ACTION_CONCURRENCY = 4, then trace how upload options are passed; done means callers can provide concurrency while the default remains 4 and the relevant behavior is covered by the existing tests.

Written by the indexing model from the issue text.