Expose brackets and template tag name

Some editor features requires the abillity to capture the brackets
independent from the tag name. e.g. Zed captures `<` as brackets and
highlight them different from the tag name. It uses it to highlight the
opposite opening/closing pair when the cursor is on one of the brackets.

Author: mogstad

grammar.js

@@ -35,9 +35,9 @@ module.exports = grammar(TypeScript, {
         field("close_tag", $.glimmer_closing_tag),
       ),
 
-    _glimmer_template_content: (_) => /.{1,}/,
-    glimmer_opening_tag: (_) => "<template>",
-    glimmer_closing_tag: (_) => "</template>",
+    glimmer_opening_tag: ($) => seq("<", $.glimmer_template_tag_name, ">"),
+    glimmer_closing_tag: ($) => seq("</", $.glimmer_template_tag_name, ">"),
+    glimmer_template_tag_name: (_) => "template",
 
     /**
      * 2. Any Expression.

src/grammar.json

@@ -2790,12 +2790,38 @@
       "value": ".{1,}"
     },
     "glimmer_opening_tag": {
-      "type": "STRING",
-      "value": "<template>"
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "<"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "glimmer_template_tag_name"
+        },
+        {
+          "type": "STRING",
+          "value": ">"
+        }
+      ]
     },
     "glimmer_closing_tag": {
-      "type": "STRING",
-      "value": "</template>"
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "</"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "glimmer_template_tag_name"
+        },
+        {
+          "type": "STRING",
+          "value": ">"
+        }
+      ]
     },
     "_jsx_element": {
       "type": "CHOICE",
@@ -11137,6 +11163,10 @@
       },
       "named": true,
       "value": "type_identifier"
+    },
+    "glimmer_template_tag_name": {
+      "type": "STRING",
+      "value": "template"
     }
   },
   "extras": [

src/node-types.json

@@ -2727,6 +2727,36 @@
       }
     }
   },
+  {
+    "type": "glimmer_closing_tag",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": false,
+      "required": true,
+      "types": [
+        {
+          "type": "glimmer_template_tag_name",
+          "named": true
+        }
+      ]
+    }
+  },
+  {
+    "type": "glimmer_opening_tag",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": false,
+      "required": true,
+      "types": [
+        {
+          "type": "glimmer_template_tag_name",
+          "named": true
+        }
+      ]
+    }
+  },
   {
     "type": "glimmer_template",
     "named": true,
@@ -5573,6 +5603,10 @@
     "type": "<",
     "named": false
   },
+  {
+    "type": "</",
+    "named": false
+  },
   {
     "type": "<<",
     "named": false
@@ -5798,11 +5832,7 @@
     "named": false
   },
   {
-    "type": "glimmer_closing_tag",
-    "named": true
-  },
-  {
-    "type": "glimmer_opening_tag",
+    "type": "glimmer_template_tag_name",
     "named": true
   },
   {