restore and fix zig bindings

bindings/zig/root.zig

@@ -0,0 +1,5 @@
+extern fn tree_sitter_c() callconv(.c) *const anyopaque;
+
+pub fn language() *const anyopaque {
+    return tree_sitter_c();
+}

bindings/zig/test.zig

@@ -0,0 +1,17 @@
+const testing = @import("std").testing;
+
+const ts = @import("tree-sitter");
+const root = @import("tree-sitter-c");
+const Language = ts.Language;
+const Parser = ts.Parser;
+
+test "can load grammar" {
+    const parser = Parser.create();
+    defer parser.destroy();
+
+    const lang: *const ts.Language = @ptrCast(root.language());
+    defer lang.destroy();
+
+    try testing.expectEqual(void{}, parser.setLanguage(lang));
+    try testing.expectEqual(lang, parser.getLanguage());
+}

tree-sitter.json

@@ -38,6 +38,7 @@
     "node": true,
     "python": true,
     "rust": true,
-    "swift": true
+    "swift": true,
+    "zig": true
   }
 }