fix: Fix String.ReplaceAll (#1705)

Author: spotandjake

compiler/test/stdlib/string.test.gr

@@ -238,6 +238,7 @@ assert String.replaceAll("/", "\/", "/test/test/test/") ==
   "\/test\/test\/test\/"
 assert String.replaceAll(",", "|", "test,test,test") == "test|test|test"
 
+assert String.replaceAll("MeowMeow", "Meow", "MeowMeowMeowMeow") == "MeowMeow"
 let processBytes = b => {
   let ret = Array.make(Bytes.length(b), 0us)
   for (let mut i = 0; i < Bytes.length(b); i += 1) {

stdlib/string.gr

@@ -1052,6 +1052,8 @@ provide let replaceAll =
         found = true
         foundCount += 1n
         foundIndexes = [tagSimpleNumber(foundIndex), ...foundIndexes]
+        foundIndex -= patternLen - 1n
+        i -= patternLen - 1n
       }
     }
     if (found) {