Fix grid resize striped area length with per-axis gap (#6563)

**Problem:**

When changing the grid gap via the canvas the row/column specific gap is
set (or using the split gap in the inspector), but it's not taken into
account when calculating the striped area length for grid resize.

**Fix:**

Take the `rowGap` / `columnGap` props into account when calculating the
striped area length in addition to the `gap` shorthand.

Fixes #6562

editor/src/components/canvas/controls/grid-controls.tsx

@@ -532,7 +532,8 @@ export const GridRowColumnResizingControlsComponent = ({
  gap={grid.columnGap ?? grid.gap}
  padding={grid.padding}
  stripedAreaLength={
- getStripedAreaLength(grid.gridTemplateRows, grid.gap ?? 0) ?? grid.frame.height
+ getStripedAreaLength(grid.gridTemplateRows, grid.rowGap ?? grid.gap ?? 0) ??
+ grid.frame.height
  }
  alignContent={grid.justifyContent}
  justifyContent={grid.alignContent}
@@ -550,7 +551,8 @@ export const GridRowColumnResizingControlsComponent = ({
  gap={grid.rowGap ?? grid.gap}
  padding={grid.padding}
  stripedAreaLength={
- getStripedAreaLength(grid.gridTemplateColumns, grid.gap ?? 0) ?? grid.frame.width
+ getStripedAreaLength(grid.gridTemplateColumns, grid.columnGap ?? grid.gap ?? 0) ??
+ grid.frame.width
  }
  alignContent={grid.alignContent}
  justifyContent={grid.justifyContent}