Internally hosted dashboards - update support panel to not force GitHub repo link

[rmbielby]

Is your feature request related to a problem? Please describe.

Some analysts are keen to use the template for internal dashboards. These mostly do not have GitHub repositories, so can not provide a working GitHub link for using the support panel.

Describe the solution you'd like

I can think of two possible elements:

• add a flag on support_panel() along the lines of internal_only = FALSE, which analysts working on internal only dashboards can set to true. That should then removes the GitHub repo requirement.
• Optional extra would be to keep the validation, but switch to allowing repos in the DfE Azure DevOps areas as well as a GitHub option.

[cjrace]

I think the latter approach of just extending the validation to include devops (though be wary there are multiple instances used!) is probably the simplest / best value for time effort