Modules: Add remaining list API functions (#8439)

List functions operating on elements by index:

* RM_ListGet
* RM_ListSet
* RM_ListInsert
* RM_ListDelete

Iteration is done using a simple for loop over indices.
The index based functions use an internal iterator as an optimization.
This is explained in the docs:

```
 * Many of the list functions access elements by index. Since a list is in
 * essence a doubly-linked list, accessing elements by index is generally an
 * O(N) operation. However, if elements are accessed sequentially or with
 * indices close together, the functions are optimized to seek the index from
 * the previous index, rather than seeking from the ends of the list.
 *
 * This enables iteration to be done efficiently using a simple for loop:
 *
 *     long n = RM_ValueLength(key);
 *     for (long i = 0; i < n; i++) {
 *         RedisModuleString *elem = RedisModule_ListGet(key, i);
 *         // Do stuff...
 *     }
```

1 files changed, 15 insertions, 4 deletions

diff --git a/src/quicklist.c b/src/quicklist.c
index ec5409533..c63b35468 100644
--- a/src/quicklist.c
+++ b/src/quicklist.c
@@ -673,6 +673,15 @@ void quicklistDelEntry(quicklistIter *iter, quicklistEntry *entry) {
      *  quicklistNext() will jump to the next node. */
 }
 
+/* Replace quicklist entry by 'data' with length 'sz'. */
+void quicklistReplaceEntry(quicklist *quicklist, quicklistEntry *entry,
+                           void *data, int sz) {
+    /* quicklistNext() and quicklistIndex() provide an uncompressed node */
+    entry->node->zl = ziplistReplace(entry->node->zl, entry->zi, data, sz);
+    quicklistNodeUpdateSz(entry->node);
+    quicklistCompress(quicklist, entry->node);
+}
+
 /* Replace quicklist entry at offset 'index' by 'data' with length 'sz'.
  *
  * Returns 1 if replace happened.
@@ -681,10 +690,7 @@ int quicklistReplaceAtIndex(quicklist *quicklist, long index, void *data,
                             int sz) {
     quicklistEntry entry;
     if (likely(quicklistIndex(quicklist, index, &entry))) {
-        /* quicklistIndex provides an uncompressed node */
-        entry.node->zl = ziplistReplace(entry.node->zl, entry.zi, data, sz);
-        quicklistNodeUpdateSz(entry.node);
-        quicklistCompress(quicklist, entry.node);
+        quicklistReplaceEntry(quicklist, &entry, data, sz);
         return 1;
     } else {
         return 0;
@@ -1189,6 +1195,11 @@ int quicklistNext(quicklistIter *iter, quicklistEntry *entry) {
     }
 }
 
+/* Sets the direction of a quicklist iterator. */
+void quicklistSetDirection(quicklistIter *iter, int direction) {
+    iter->direction = direction;
+}
+
 /* Duplicate the quicklist.
  * On success a copy of the original quicklist is returned.
  *