Possible to use OAuth2 bearer tokens with `--registry`?

### Description of the bug:

We have a registry hosted on GitLab. GitLab uses an OAuth2 style bearer token header to authenticate: `Bearer: `. It does not appear to support basic HTTP auth. Is there any method for inserting this header into the registry requests?

### Which category does this issue belong to?

External Dependency

### What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Set up a registry on a private GitLab repository and pass it to `--registry`

### Which operating system are you running Bazel on?

Ubuntu

### What is the output of `bazel info release`?

release 7.1.1

### If `bazel info release` returns `development version` or `(@non-git)`, tell us how you built Bazel.

_No response_

### What's the output of `git remote get-url origin; git rev-parse HEAD` ?

_No response_

### Is this a regression? If yes, please try to identify the Bazel commit where the bug was introduced.

_No response_

### Have you found anything relevant by searching the web?

Related to #16659

### Any other information, logs, or outputs that you want to share?

_No response_