Extract PHP support into an extension (#9966)

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

There's a small workaround necessary in order for us to provide the
`language_ids` on the `LspAdapter` that are needed for the language
server to run properly. Eventually we'll want to build this into the
extension API, but for now we're just hard-coding it on the host side.

Release Notes:

- Removed built-in support for PHP, in favor of making it available as
an extension. The PHP extension will be suggested for download when you
open a `.php` file.

Cargo.lock

@@ -5458,7 +5458,6 @@ dependencies = [
  "tree-sitter-nix",
  "tree-sitter-nu",
  "tree-sitter-ocaml",
- "tree-sitter-php",
  "tree-sitter-proto",
  "tree-sitter-python",
  "tree-sitter-racket",
@@ -10587,16 +10586,6 @@ dependencies = [
  "tree-sitter",
 ]
 
-[[package]]
-name = "tree-sitter-php"
-version = "0.21.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0db3788e709a5adfb583683a4b686a084e41a0f9e5a2fcb9a8e358f11481036a"
-dependencies = [
- "cc",
- "tree-sitter",
-]
-
 [[package]]
 name = "tree-sitter-proto"
 version = "0.0.2"
@@ -12708,6 +12697,13 @@ dependencies = [
  "zed_extension_api 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "zed_php"
+version = "0.0.1"
+dependencies = [
+ "zed_extension_api 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "zed_prisma"
 version = "0.0.1"