Themes: Add 3 and update 2 shadow presets in theme.json.

Adds Deep, Outlined, and Crisp default shadow presets to Core's `theme.json` file.

Updates the Natural and Sharp `'shadow'` styles.

These shadow presets are used to populate the Shadow tools in the Site Editor's Global Styles UI.

References:
* [WordPress/gutenberg#46502 Gutenberg PR 46502]

Follow-up to [55176].

Props franz00, madhudollu, ajlende, beafialho, costdev, dhrupo, fabiankaegy, hellofromTonya, jameskoster, joen, kellychoffman, mamaduka, mtias, oandregal, priethor, richtabor, scruffian. 
Fixes #57708.
See #57559.

git-svn-id: https://develop.svn.wordpress.org/trunk@55405 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/theme.json

@@ -326,16 +326,32 @@
 			}
 		},
 		"shadow": {
+			"defaultPresets": true,
 			"presets": [
 				{
 					"name": "Natural",
 					"slug": "natural",
-					"shadow": "0 .2rem .3rem 0 rgba(0,0,0, 0.3), 0 .5rem .6rem 0 rgba(0,0,0, 0.4)"
+					"shadow": "6px 6px 9px rgba(0, 0, 0, 0.2)"
+				},
+				{
+					"name": "Deep",
+					"slug": "deep",
+					"shadow": "12px 12px 50px rgba(0, 0, 0, 0.4)"
 				},
 				{
 					"name": "Sharp",
 					"slug": "sharp",
-					"shadow": ".5rem .5rem 0 0 rgba(0,0,0, 0.4)"
+					"shadow": "6px 6px 0px rgba(0, 0, 0, 0.2)"
+				},
+				{
+					"name": "Outlined",
+					"slug": "outlined",
+					"shadow": "6px 6px 0px -3px rgba(255, 255, 255, 1), 6px 6px rgba(0, 0, 0, 1)"
+				},
+				{
+					"name": "Crisp",
+					"slug": "crisp",
+					"shadow": "6px 6px 0px rgba(0, 0, 0, 1)"
 				}
 			]
 		},