AK: Make quick_sort() a little more ergonomic

Now it actually defaults to "a < b" comparison, instead of forcing you
to provide a trivial less-than comparator. Also you can pass in any
collection type that has .begin() and .end() and we'll sort it for you.

Userland/cut.cpp

@@ -221,7 +221,7 @@ int main(int argc, char** argv)
 
     Vector<Index> byte_vector;
     expand_list(tokens, byte_vector);
-    quick_sort(byte_vector.begin(), byte_vector.end(), [](auto& a, auto& b) { return a.m_from < b.m_from; });
+    quick_sort(byte_vector, [](auto& a, auto& b) { return a.m_from < b.m_from; });
     /* Process each file */
     for (auto& file : files) {
         cut_file(file, byte_vector);

Userland/ls.cpp

@@ -326,7 +326,7 @@ int do_file_system_object_long(const char* path)
         files.append(move(metadata));
     }
 
-    quick_sort(files.begin(), files.end(), [](auto& a, auto& b) {
+    quick_sort(files, [](auto& a, auto& b) {
         if (flag_sort_by_timestamp) {
             if (flag_reverse_sort)
                 return a.stat.st_mtime > b.stat.st_mtime;
@@ -382,7 +382,7 @@ int do_file_system_object_short(const char* path)
         if (names.last().length() > longest_name)
             longest_name = name.length();
     }
-    quick_sort(names.begin(), names.end(), [](auto& a, auto& b) { return a < b; });
+    quick_sort(names);
 
     size_t printed_on_row = 0;
     size_t nprinted = 0;

Userland/sort.cpp

@@ -50,7 +50,7 @@ int main(int argc, char** argv)
         lines.append(buffer);
     }
 
-    quick_sort(lines.begin(), lines.end(), [](auto& a, auto& b) {
+    quick_sort(lines, [](auto& a, auto& b) {
         return strcmp(a.characters(), b.characters()) < 0;
     });
 

Userland/top.cpp

@@ -184,7 +184,7 @@ int main(int, char**)
             threads.append(&it.value);
         }
 
-        quick_sort(threads.begin(), threads.end(), [](auto* p1, auto* p2) {
+        quick_sort(threads, [](auto* p1, auto* p2) {
             return p2->times_scheduled_since_prev < p1->times_scheduled_since_prev;
         });