Match the primary button disabled state to Core's color contrast (#16103

)

* See #15280. This fixes the primary button's disabled view to match core primary disabled buttons.

* Removed unecessary opacity attribute in css.

* Revising tint and shade Sass values to get closer to Core.

* Minor CSS edit to remove text shadow from disabled buttons.

* Added active state to disabled state to remove active change of color.

* Fixed the focus state of disabled primary button to keep the disabled text color.

* A few minor CSS tweaks to fix the border inset shadow.

* Move disabled focus styles alongside other disabled rules.

* Ensure disabled state persists for alternate color schemes.

packages/components/src/button/style.scss

@@ -101,12 +101,30 @@
 		}
 
 		&:disabled,
-		&[aria-disabled="true"] {
-			color: color(theme(button) tint(30%));
-			background: color(theme(button) shade(30%));
-			border-color: color(theme(button) shade(20%));
+		&:disabled:active:enabled,
+		&[aria-disabled="true"],
+		&[aria-disabled="true"]:active:enabled {
+			color: color(theme(button) tint(40%));
+			background: color(theme(button));
+			border-color: color(theme(button) shade(7%));
 			box-shadow: none;
-			text-shadow: 0 -1px 0 rgba(0, 0, 0, 0.1);
+			text-shadow: none;
+
+			// This specificity is needed to override alternate color schemes in WP-Admin.
+			&.is-button,
+			&.is-button:hover,
+			&:active:enabled {
+				box-shadow: none;
+				text-shadow: none;
+			}
+
+			&:focus:enabled {
+				color: color(theme(button) tint(40%));
+				border-color: color(theme(button) shade(7%));
+				box-shadow:
+					0 0 0 1px $white,
+					0 0 0 3px $blue-medium-focus;
+			}
 		}
 
 		&.is-busy,
@@ -171,7 +189,6 @@
 	&:disabled,
 	&[aria-disabled="true"] {
 		cursor: default;
-		opacity: 0.3;
 	}
 
 	&:focus:not(:disabled) {