[improvement] rename suffixPx to addUnit

src/utils/format/unit.ts

@@ -1,7 +1,7 @@
 import { isDef } from '..';
 import { isNumber } from '../validate/number';
 
-export function suffixPx(value?: string | number): string | undefined {
+export function addUnit(value?: string | number): string | undefined {
   if (!isDef(value)) {
     return undefined;
   }