AK: Replace the mutable String::replace API with an immutable version

This removes the awkward String::replace API which was the only String
API which mutated the String and replaces it with a new immutable
version that returns a new String with the replacements applied. This
also fixes a couple of UAFs that were caused by the use of this API.

As an optimization an equivalent StringView::replace API was also added
to remove an unnecessary String allocations in the format of:
`String { view }.replace(...);`

1 files changed, 6 insertions, 10 deletions

diff --git a/Tests/AK/TestString.cpp b/Tests/AK/TestString.cpp
index d5e7c970bb..fc55df1a5a 100644
--- a/Tests/AK/TestString.cpp
+++ b/Tests/AK/TestString.cpp
@@ -146,25 +146,21 @@ TEST_CASE(flystring)
 TEST_CASE(replace)
 {
     String test_string = "Well, hello Friends!";
-    u32 replacements = test_string.replace("Friends", "Testers");
-    EXPECT(replacements == 1);
+
+    test_string = test_string.replace("Friends", "Testers");
     EXPECT(test_string == "Well, hello Testers!");
 
-    replacements = test_string.replace("ell", "e're", true);
-    EXPECT(replacements == 2);
+    test_string = test_string.replace("ell", "e're", true);
     EXPECT(test_string == "We're, he'reo Testers!");
 
-    replacements = test_string.replace("!", " :^)");
-    EXPECT(replacements == 1);
+    test_string = test_string.replace("!", " :^)");
     EXPECT(test_string == "We're, he'reo Testers :^)");
 
     test_string = String("111._.111._.111");
-    replacements = test_string.replace("111", "|||", true);
-    EXPECT(replacements == 3);
+    test_string = test_string.replace("111", "|||", true);
     EXPECT(test_string == "|||._.|||._.|||");
 
-    replacements = test_string.replace("|||", "111");
-    EXPECT(replacements == 1);
+    test_string = test_string.replace("|||", "111");
     EXPECT(test_string == "111._.|||._.|||");
 }