typeahead: Replace code block language hint text with more clear options

This commit
- Replace the blank option with an italicized option that's the current
   default language, if there is one selected with "default" label.
- Make the "text" option more informative by adding (no highlighting)
   to the label.
- Remove the hint for "text".
- Prioritize as left to right, before start typing:
   blank/default language, text, quote, spoiler, math, everything else...

fixes: #33682

tools/setup/build_pygments_data

@@ -6,6 +6,7 @@ from pygments.lexers import get_all_lexers
 
 ZULIP_PATH = os.path.join(os.path.dirname(os.path.abspath(__file__)), "../../")
 # The current priorities data set is based on StackOverflow's 2020 survey.
+# We also prioritize text, quote, math, spoiler over others to enhance UX.
 DATA_PATH = os.path.join(ZULIP_PATH, "tools", "setup", "lang.json")
 OUT_PATH = os.path.join(ZULIP_PATH, "web", "generated", "pygments_data.json")
 

tools/setup/lang.json

@@ -1,5 +1,6 @@
 {
     "default": {
+        "text": 31,
         "javascript": 27,
         "python": 26,
         "java": 25,
@@ -30,9 +31,9 @@
     },
     "custom": {
         "latex": 10,
-        "math": 5,
-        "quote": 5,
-        "spoiler": 5
+        "math": 28,
+        "quote": 30,
+        "spoiler": 29
     },
     "aliases": {
         "js": 27,