Set a proper <title> when generating PDF

### Description

Currently we do not override the element when rendering PDF. It stays at the default from [Index.cshtml](https://github.com/Altinn/altinn-studio/blob/a470b27fedb54d6d9a3d7397eb03b203cb4cddc6/src/App/template/src/App/views/Home/Index.cshtml#L9) which is just `{org}- {app}`. Since https://github.com/Altinn/app-lib-dotnet/issues/196 was resolved the PDF document title (metadata) is controlled by the html <title> element.

At least the default could be a bit better, but it should probably be [configurable](https://github.com/Altinn/app-lib-dotnet/issues/561) or at least a little more dynamic, since there could be multiple PDFs for an instance, and potentially [separate PDFs for subform entries](https://github.com/Altinn/app-lib-dotnet/issues/1016).

### Additional Information

_No response_

Start with the title element in src/App/template/src/App/views/Home/Index.cshtml and trace how the PDF-rendering flow uses it. Review the linked app-lib-dotnet issues for the intended configurability and multiple-PDF behavior; done means generated PDFs have an intentional, non-default document title.

Written by the indexing model from the issue text.