Improve wrapPanels

[v-zhuravlev]

Initial implementation (#110 ) of wrapPanels didn't support panels inside rows. This PR adds support for panels inside rows, so wrapPanels can properly calculate grid coordinates with collapsed rows as well.
Useful in conjunction with g.util.panel.resolveCollapsedFlagOnRows:

        g.dashboard.new('Dash')
        + g.dashboard.withPanels(
          g.util.panel.resolveCollapsedFlagOnRows(
            g.util.grid.wrapPanels(
              [
              g.panel.row.new('row1')
              + g.panel.row.withCollapsed(true)
                + g.panel.row.withPanels(panels1),
              g.panel.row.new('row2')
              + g.panel.row.withCollapsed(true)
                + g.panel.row.withPanels(panels2),
              ]
            )
          ),
        ),
    },

[Duologic]

Looks ok.

[v-zhuravlev]

@Duologic is it ready to be merged?