Update textmate parser (#1151)

Updates the textmate parser to handle `template_string_declaration`.

The previous version defined a separate `block_string` rule that could
be shared across use sites. However, it was easier to define a
special-purpose block string handler within
`template_string_definition`, that could coordinate with the
`template_string_definition`. Specifically, the inlined block string
parser uses a lookahead parser to scan for the ending `"#` without
consuming it, so that `"#` can be owned by the outer
`template_string_definition` parser.

This PR:
![Screenshot 2024-11-08 at 4 34
02 PM](https://github.com/user-attachments/assets/79733f8b-43ad-4df5-8758-8cb874a259ca)

(Multiline parameters still highlight correctly)
<img width="368" alt="Screenshot 2024-11-09 at 10 04 04 AM"
src="https://github.com/user-attachments/assets/49d337a3-f89f-47c5-81bb-9045070ab78c">

canary prior to this PR:
![Screenshot 2024-11-08 at 4 35
19 PM](https://github.com/user-attachments/assets/979f58d8-d554-4751-92a1-3de63c6c66f1)

canary prior to the last change to the textmate grammar
(https://github.com/BoundaryML/baml/pull/1130/files):
![Screenshot 2024-11-08 at 4 36
46 PM](https://github.com/user-attachments/assets/c450c170-af6c-4294-99d6-2c3521682221)

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----

> [!IMPORTANT]
> Updates `template_string_declaration` in `baml.tmLanguage.json` to
handle block strings directly, removing the separate `block_string`
rule.
> 
>   - **Behavior**:
> - Updates `template_string_declaration` in `baml.tmLanguage.json` to
handle block strings with a lookahead parser for ending `"#`.
> - Removes separate `block_string` rule, integrating its functionality
directly into `template_string_declaration`.
>   - **Patterns**:
> - Adjusts `end` pattern in `template_string_declaration` to `"#{1,3}`.
> - Adds inline block string handling with `begin` and `end` patterns
for `#{1,3}"` and `"#{1,3}` respectively.
>   - **Misc**:
>     - Removes `block_string` from the repository.
> 
> <sup>This description was created by </sup>[<img alt="Ellipsis"
src="https://img.shields.io/badge/Ellipsis-blue?color=175173">](https://www.ellipsis.dev?ref=BoundaryML%2Fbaml&utm_source=github&utm_medium=referral)<sup>
for 2663d77. It will automatically
update as commits are pushed.</sup>


<!-- ELLIPSIS_HIDDEN -->

typescript/vscode-ext/packages/syntaxes/baml.tmLanguage.json

@@ -83,13 +83,25 @@
         "1": { "name": "storage.type.declaration.function" },
         "2": { "name": "entity.name.function" }
       },
-      "end": "(\")(#)",
+      "end": "(\")(#{1,3})",
       "endCaptures": {
-        "1": { "name": "string.quoted.block.baml" },
-        "2": { "name": "string.quoted.block.baml" }
+        "0": { "name": "string.quoted.block.baml" }
       },
-      "name": "string.quoted.block.baml",
-      "patterns": [{ "include": "#comment" }, { "include": "#function_parameters" }, { "include": "#block_string" }]
+      "patterns": [
+        { "include": "#comment" },
+        { "include": "#function_parameters" },
+        {
+          "begin": "(#{1,3}\")",
+          "beginCaptures": {
+            "0": { "name": "string.quoted.block.baml" }
+          },
+          "end": "(?=\"#{1,3})",
+          "contentName": "string.quoted.block.baml",
+          "patterns": [
+            { "include": "source.baml-jinja" }
+          ]
+        }
+      ]
     },
     "function_declaration": {
       "comment": "Function declaration",
@@ -576,18 +588,6 @@
         }
       ]
     },
-    "block_string": {
-      "begin": "(#(\"){1,3})",
-      "beginCaptures": {
-        "1": { "name": "string.quoted.block.baml.startquote" }
-      },
-      "end": "((\"){1,3}#)",
-      "endCaptures": {
-        "1": { "name": "string.quoted.block.baml.endquote" }
-      },
-      "contentName": "string.quoted.block.baml",
-      "patterns": [{ "include": "source.baml-jinja" }]
-    },
     "block_string_pair": {
       "begin": "(\\w+)?\\s+(#(\"){1,3})",
       "beginCaptures": {