MISC: Remove isString utility function (#1185)

src/utils/helpers/string.ts

@@ -1,13 +1,3 @@
-// We can probably get rid of isString in favor of just checking typeof value==="string".
-// We are not and should not ever be using `new String()` for anything. Will remove in 2.3.1
-/**
- * Checks whether the value passed in can be considered a string.
- * @param value The value to check if it is a string.
- */
-export function isString(value: unknown): value is string {
-  return typeof value === "string" || value instanceof String;
-}
-
 /** Removes a single layer of matching single or double quotes, if present. */
 export function trimQuotes(value: string): string {
   if (value.length < 2) return value;