Add NavigationTag on GridRows and add ability to select a GridRow

[adrian-ursu]

I feel we need additional control over the use of rows for the benefit of reusing some of the rows already defined in other pages.

I would like to be able to set up a NavigationTag on a Row and be able to replace RenderGridRow("id") with RenderGridRowByNavigationTag("NavigationTag").

Also, it may be useful to be able to select a GridRow from a page, just like we are now able to select a specific Paragraph of a page. However, this will require the ability to set up a Name/Title for each GridRow.

Thank you,
Adrian