Extract HTML support into an extension (#10130)

This PR extracts HTML support into an extension and removes the built-in
HTML support from Zed.

Release Notes:

- Removed built-in support for HTML, in favor of making it available as
an extension. The HTML extension will be suggested for download when you
open a `.html`, `.htm`, or `.shtml` file.

Cargo.lock

@@ -5348,7 +5348,6 @@ dependencies = [
  "tree-sitter-gowork",
  "tree-sitter-hcl",
  "tree-sitter-heex",
- "tree-sitter-html",
  "tree-sitter-jsdoc",
  "tree-sitter-json 0.20.0",
  "tree-sitter-lua",
@@ -12537,6 +12536,13 @@ dependencies = [
  "zed_extension_api 0.0.4",
 ]
 
+[[package]]
+name = "zed_html"
+version = "0.0.1"
+dependencies = [
+ "zed_extension_api 0.0.4",
+]
+
 [[package]]
 name = "zed_php"
 version = "0.0.1"