Create a function that takes a string and returns a string with its letters in alphabetical order.
alphabetSoup("hello") ➞ "ehllo"
alphabetSoup("edabit") ➞ "abdeit"
alphabetSoup("hacker") ➞ "acehkr"
alphabetSoup("geek") ➞ "eegk"
alphabetSoup("javascript") ➞ "aacijprstv"You can assume numbers and punctuation symbols won't be included in test cases. You'll only have to deal with single word, alphabetic characters.