Refactor Syntax

This commit...

1. introduces common `meta.template.twig` applied scope accross Text/HTML/JS/CSS
2. adjusts snippet selectors
3. adds some helper key bindings
4. applies syntax specific toggle comment rules to apply Twig comments
   by default but retain original syntax's block comment as variant 2.
5. renames contexts to use hyphens as subword-separators
6. reorders contexts following lessons learned from Jinja and other template
   syntaxes
7. apply `meta.embedded` to tags and `source.twig` to their content.
8. fix various smaller highlighting bugs

.github/workflows/syntax_test.yml

@@ -27,12 +27,14 @@ jobs:
       strategy:
         matrix:
           include:
-            - build: 4142
-              packages: v4142
-            - build: 4170
-              packages: v4170
-            - build: 4173
-              packages: v4173
+            - build: 4152
+              packages: v4152
+            - build: 4169
+              packages: v4169
+            - build: 4180
+              packages: v4180
+            - build: latest
+              packages: master
       steps:
         - uses: actions/checkout@v4
         - uses: SublimeText/syntax-test-action@v2