Use `d3-utils/set-style` instead of internal version

The current [`grid-sheet`](https://github.com/zambezi/grid/blob/78c1d1d78806eb3f04ce0641df38468c7a812d4c/src/grid-sheet.js) component has been pulled into [d3-utils](https://github.com/zambezi/d3-utils/pull/9)

We should use the external component instead of supporting two versions of the same functionality.