enh(cpp) add flat_map and flat_set c++23 new features (highlightjs#4127)

Author: jvlavan

CHANGES.md

@@ -21,7 +21,8 @@ Core Grammars:
 - fix(typescript) - Fixedoptional property not highlighted correctly  [Dxuian]
 - fix(ruby) - fix `|=` operator false positives (as block arguments) [Aboobacker MK]
 - fix(sql) - Fixed sql primary key and foreign key spacing issue   [Dxuian]
-
+- fix(cpp) added flat_set and flat_map as a part of cpp 23 version [Lavan]
+  
 New Grammars:
 
 - added 3rd party TTCN-3 grammar to SUPPORTED_LANGUAGES [Osmocom][]
@@ -53,6 +54,7 @@ CONTRIBUTORS
 [Sainan]: https://github.com/Sainan
 [Osmocom]: https://github.com/osmocom
 [Álvaro Mondéjar]: https://github.com/mondeja
+[Lavan]: https://github.com/jvlavan
 
 
 ## Version 11.10.0

src/languages/cpp.js

@@ -247,6 +247,8 @@ export default function(hljs) {
     'counting_semaphore',
     'deque',
     'false_type',
+    'flat_map',
+    'flat_set',
     'future',
     'imaginary',
     'initializer_list',
@@ -572,7 +574,7 @@ export default function(hljs) {
       [
         PREPROCESSOR,
         { // containers: ie, `vector <int> rooms (9);`
-          begin: '\\b(deque|list|queue|priority_queue|pair|stack|vector|map|set|bitset|multiset|multimap|unordered_map|unordered_set|unordered_multiset|unordered_multimap|array|tuple|optional|variant|function)\\s*<(?!<)',
+          begin: '\\b(deque|list|queue|priority_queue|pair|stack|vector|map|set|bitset|multiset|multimap|unordered_map|unordered_set|unordered_multiset|unordered_multimap|array|tuple|optional|variant|function|flat_map|flat_set)\\s*<(?!<)',
           end: '>',
           keywords: CPP_KEYWORDS,
           contains: [