feat(language): add tamil old (@VIZL-23) (monkeytypegame#6141)

### Description

Added the version of Old Tamil Language(similar to old English,these
words were used in plays and poems) words to the group of Tamil

### Checks

- [x] Adding a language or a theme?
- [x] If is a language, did you edit `_list.json`, `_groups.json` and
add `languages.json`?
- [x] Make sure to include your GitHub username prefixed with @ inside
parentheses at the end of the PR title.

Author: VIZL-23

frontend/static/languages/_groups.json

@@ -195,7 +195,7 @@
   },
   {
     "name": "tamil",
-    "languages": ["tamil", "tamil_1k", "tanglish"]
+    "languages": ["tamil", "tamil_1k", "tanglish", "tamil_old"]
   },
   {
     "name": "kannada",

frontend/static/languages/_list.json

@@ -89,6 +89,7 @@
   ,"tamil"
   ,"tamil_1k"
   ,"tanglish"
+  ,"tamil_old"
   ,"telugu"
   ,"telugu_1k"
   ,"greek"