Clean up the datagrid CSS organization and add namespaced variables.

Review Request #10665 — Created Aug. 15, 2019 and submitted

Review Board

This updates the datagrids code to introduce a #rb-ns-ui.datagrids
namespace containing the various margins, paddings, colors, and other
styles used by our datagrid. This builds upon the new
#djblets-ns-ui.datagrids namespace in Djblets, extending those to give
us a single place where we can look up all variables.

Some of the datagrid code has been shuffled around in the process. The
datagrid classes have been made flatter and more reusable. Some styles
had to be updated to account for this, as specificity changed.

It's not a full clean-up, and documentation is not being added at this
stage. Eventually we'll want to rethink the component structure and
styling of datagrids in Djblets, and rethink some of the add-on classes
we've introduced here, but that's a change for another day.

Checked all the datagrids and the affected columns, making sure it all
appeared to render correctly.

  1. Ship It!
Review request changed

Status: Closed (submitted)

Change Summary:

Pushed to release-4.0.x (d3c6597)