fix(number-box): make the content alignment adjustable (#3487)

Author: Arukuen

src/block/number-box/style.scss

@@ -3,7 +3,7 @@
 .stk-block-number-box__container,
 div.stk-block-number-box__text {
 	display: inline-flex;
-	justify-content: center;
+	justify-content: var(--stk-alignment-justify-content, center);
 	align-items: center;
 	font-weight: bold;
 	font-size: 56px;