[Feature]: Allow customization of Accept-header In RemoteUrl

Feature Description

Currently, the Accept-header is hard coded in RemoteUrl:

    private static final String ACCEPT_HEADER_VALUE = "application/json, application/yaml, */*";

Users can't change it, even if their Api might require different headers

Use Case

When using the GH file api, one has to set the Accept-header to application/vnd.github.v3.raw to retrieve the raw file content. This is currently not possible.

Suggested Solution (optional)

The easiest solution would be to back-off if the user provided its own header using the already existing List<AuthorizationValue> auths:

    private static void setRequestHeaders(List<AuthorizationValue> header, URLConnection conn) {
        conn.setRequestProperty("Accept", ACCEPT_HEADER_VALUE);
        conn.setRequestProperty("User-Agent", USER_AGENT_HEADER_VALUE);
        
        // allows user to override defaults
        for (AuthorizationValue item : header) {
            conn.setRequestProperty(item.getKeyName(), item.getValue());
        }

    }

I'am happy to provide the PR if you agree with this course of action

Alternatives Considered

No workaround exists since the behavior is hard coded

Additional Context

Checklist

• I have searched the existing issues to ensure this is not a duplicate.
• This feature would be useful to more than just my use case.
• I have provided enough detail for the maintainers to understand the scope of the request.

Start by locating RemoteUrl and its setRequestHeaders method, then read how the existing AuthorizationValue list is passed into request setup. The change is done when callers can override the default Accept header, including for the GitHub raw-file use case, without removing the existing default behavior.