MudTable requires a FooterContent

Is your feature request related to a problem? Please describe. I need to place a footer row, but the current MudTable control doesn’t allow to do so. I also need to place multiple rows, both on header and footer, so both should allow the user to place the row tag manually inside the fragment.

Describe the solution you’d like Change MudTableBase.HeaderContent to be a new type of MudTableHeader and add a new FooterContent to be of type MudFooterContent that behave similar to MudTr. Both should have an attribute called “SingleRow” defaulted to true (for backward compatibility) that will or won’t automatically create a tr tag, and of course Class and other common attributes like MudTr already does. If the user sets SingleRow="false", should provide his own MudTr or plain HTML code, giving more freedom. The control itself should still render thead and tfoot tags.

Describe alternatives you’ve considered I’ve seen the PR https://github.com/Garderoben/MudBlazor/pull/888 and the discussion about replacing MudTable. I don’t think we should merge/replace them, other then being a compatibility hell (although it’s a young project and it’s something I think MudBlazor can afford). They can follow two different paths and diverge even more, one being simpler and fast while the other being more prone to customization. In the current state, however, MudDataTable still doesn’t allow for multi-row footer/header.