[Monaco] Use syntax highlighting for .srt (#35651)

* [FilePreview] Use syntax highlighting for .srt

* Change customTokenColors to customTokenThemeRules

* Ignore text on the same line as a timestamp

* Update tokenization rules

src/Monaco/customLanguages/srt.js

@@ -0,0 +1,29 @@
+export function srtDefinition() {
+    return {
+        tokenizer: {
+            root: [
+                [/\s*\d+/, 'number', '@block']
+            ],
+            
+            block: [
+                [/^\d{2}:\d{2}:\d{2},\d{3} --> \d{2}:\d{2}:\d{2},\d{3}/, {
+                    cases: {
+                        '@eos': {token: 'type.identifier', next: '@subtitle'},
+                        '@default': {token: 'type.identifier', next: '@ignore'}
+                    }
+                }],
+                [/^$/, 'string', '@pop']
+            ],
+            
+            ignore: [
+                [/.+$/, '', '@subtitle']
+            ],
+            
+            subtitle: [
+                [/^$/, 'string', '@popall'],
+                [/<\/?(?:[ibu]|font(?:\s+color="[^"]+"\s*)?)>/, 'tag'],
+                [/./, 'string']
+            ]
+        }
+    };
+}