Flag to forcifully re-fetch bzlmod registry files

### Description of the feature request:

I want to request a flag to forcifully fetch bzlmod registry files instead of relying on a local cache.

### Which category does this issue belong to?

Configurability, External Dependency

### What underlying problem are you trying to solve with this feature?

For example, suppose you have the following set up (see
[test.tar.gz](https://github.com/bazelbuild/bazel/files/13619870/test.tar.gz) )

```
# MODULE.bazel
bazel_dep(name = "mymod", version = "0.0.1")
```

and a local registry that vendors `@@mymod`:

```
# reg/modules/mymod/0.0.1/source.json
{
"type": "local_path",
"path": "mymod"
}
```

One may load files from `@@mymod` to let Bazel fetch the above `source.json`. However, after that, Bazel keeps this file in cache somewhere. So if I modify `source.json` locally, I cannot tell Bazel to forcifully fetch this `source.json` file again.

This is particularly important if I am relocating the source for a module.

I tried `bazel clean --expunge`, `rm -rf ~/.cache/bazel`, etc.; but none of them prevents Bazel from consulting this cache.

I request a flag to disable the underlying download cache.

Currently, the only workaround is to move the registry to somewhere else, then specify a different `--registry` flag to point to the new registry.

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

Linux

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

release 7.0.0-pre.20231011.2

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

N/A

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

```text
N/A
```

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

No

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

N/A

Reproduce the behavior with the attached test.tar.gz, MODULE.bazel, and the local registry's source.json, then trace the bzlmod registry fetch and cache handling used by the --registry workflow. Done means a flag can force registry files such as source.json to be fetched again after local edits, including when relocating a module source.

Written by the indexing model from the issue text.