Navigation block: Allow themes to override block library text-decorat…

…ion rule (WordPress#63406)

* Reduce specificity of navigation text decoration rule

* Apply Aaron suggestion to also lower specificity for focus/active

* Remove `:not([class*="has-text-decoration"])` from selector

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Co-authored-by: talldan <talldanwp@git.wordpress.org>
Co-authored-by: ellatrix <ellatrix@git.wordpress.org>
Co-authored-by: aaronrobertshaw <aaronrobertshaw@git.wordpress.org>

packages/block-library/src/navigation/style.scss

@@ -76,15 +76,10 @@ $navigation-icon-size: 24px;
 		}
 	}
 
-	&:where(:not([class*="has-text-decoration"])) {
-		a {
-			text-decoration: none;
-
-			&:focus,
-			&:active {
-				text-decoration: none;
-			}
-		}
+	& :where(a),
+	& :where(a:focus),
+	& :where(a:active) {
+		text-decoration: none;
 	}
 
 	// Submenu indicator.