Add standard spacing presets to Block Canvas (#7717)

block-canvas/theme.json

@@ -38,6 +38,33 @@
 			"wideSize": "1000px"
 		},
 		"spacing": {
+			"spacingSizes": [
+				{
+					"name": "Step 1",
+					"size": "0.25rem",
+					"slug": "10"
+				},
+				{
+					"name": "Step 2",
+					"size": "0.5rem",
+					"slug": "20"
+				},
+				{
+					"name": "Step 3",
+					"size": "0.75rem",
+					"slug": "30"
+				},
+				{
+					"name": "Step 4",
+					"size": "1rem",
+					"slug": "40"
+				},
+				{
+					"name": "Step 5",
+					"size": "1.25rem",
+					"slug": "50"
+				}
+			],
 			"units": ["%", "px", "em", "rem", "vh", "vw"]
 		},
 		"typography": {