Bundle redoc directly

### Describe the problem

Right now `redoc` is bundled via [drf-spectacular-sidecar](https://pypi.org/project/drf-spectacular-sidecar/). That way, we don't directly control `redoc` version, it is missing from our client code licensing info and increases Weblate storage because it pulls also Swagger which we do not use.

### Describe the solution you would like

Bundle `redoc` in `client` libraries similarly like we do with Sentry.

### Describe alternatives you have considered

_No response_

### Screenshots

_No response_

### Additional context

Once this is done:

* The `sidecar` extra can be removed:

https://github.com/WeblateOrg/weblate/blob/8841711389434737eb4406ba37d03130a720d02c/pyproject.toml#L52

* `drf_spectacular_sidecar` app should be removed from `INSTALLED_APPS` in `weblate/settings_*.py`

* The URL will need to be adjusted in:

https://github.com/WeblateOrg/weblate/blob/f60acb22de1f6f0b32a938e279e327cd205648c3/weblate/api/spectacular.py#L12-L14