cdp: improve playwright support

The getTargetInfo result must return a `targetInfo` key.

Here is an example returned by Chrome:
```json
{
  "id": 16,
  "result": {
    "targetInfo": {
      "targetId": "d93a1bbc-f906-4bbb-bb4d-a2285234b091",
      "type": "browser",
      "title": "",
      "url": "",
      "attached": true,
      "canAccessOpener": false
    }
  }
}
```

Author: krichprollsch

src/cdp/target.zig

@@ -218,9 +218,10 @@ fn closeTarget(cmd: anytype) !void {
 }
 
 fn getTargetInfo(cmd: anytype) !void {
-    const params = (try cmd.params(struct {
+    const Params = struct {
         targetId: ?[]const u8 = null,
-    })) orelse return error.InvalidParams;
+    };
+    const params: Params = (try cmd.params(Params)) orelse .{};
 
     if (params.targetId) |param_target_id| {
         const bc = cmd.browser_context orelse return error.BrowserContextNotLoaded;
@@ -230,21 +231,25 @@ fn getTargetInfo(cmd: anytype) !void {
         }
 
         return cmd.sendResult(.{
-            .targetId = target_id,
-            .type = "page",
-            .title = "",
-            .url = "",
-            .attached = true,
-            .canAccessOpener = false,
+            .targetInfo = .{
+                .targetId = target_id,
+                .type = "page",
+                .title = "",
+                .url = "",
+                .attached = true,
+                .canAccessOpener = false,
+            },
         }, .{ .include_session_id = false });
     }
 
     return cmd.sendResult(.{
-        .type = "browser",
-        .title = "",
-        .url = "",
-        .attached = true,
-        .canAccessOpener = false,
+        .targetInfo = .{
+            .type = "browser",
+            .title = "",
+            .url = "",
+            .attached = true,
+            .canAccessOpener = false,
+        },
     }, .{ .include_session_id = false });
 }
 
@@ -547,3 +552,54 @@ test "cdp.target: attachToTarget" {
         try ctx.expectSentEvent("Target.attachedToTarget", .{ .sessionId = session_id, .targetInfo = .{ .url = "chrome://newtab/", .title = "about:blank", .attached = true, .type = "page", .canAccessOpener = false, .browserContextId = "BID-9", .targetId = bc.target_id.? } }, .{});
     }
 }
+
+test "cdp.target: getTargetInfo" {
+    var ctx = testing.context();
+    defer ctx.deinit();
+
+    {
+        try ctx.processMessage(.{ .id = 9, .method = "Target.getTargetInfo" });
+        try ctx.expectSentResult(.{
+            .targetInfo = .{
+                .type = "browser",
+                .title = "",
+                .url = "",
+                .attached = true,
+                .canAccessOpener = false,
+            },
+        }, .{ .id = 9 });
+    }
+
+    {
+        try testing.expectError(error.BrowserContextNotLoaded, ctx.processMessage(.{ .id = 10, .method = "Target.getTargetInfo", .params = .{ .targetId = "X" } }));
+        try ctx.expectSentError(-31998, "BrowserContextNotLoaded", .{ .id = 10 });
+    }
+
+    const bc = try ctx.loadBrowserContext(.{ .id = "BID-9" });
+    {
+        try testing.expectError(error.TargetNotLoaded, ctx.processMessage(.{ .id = 10, .method = "Target.getTargetInfo", .params = .{ .targetId = "TID-8" } }));
+        try ctx.expectSentError(-31998, "TargetNotLoaded", .{ .id = 10 });
+    }
+
+    // pretend we createdTarget first
+    _ = try bc.session.createPage();
+    bc.target_id = "TID-A";
+    {
+        try testing.expectError(error.UnknownTargetId, ctx.processMessage(.{ .id = 10, .method = "Target.getTargetInfo", .params = .{ .targetId = "TID-8" } }));
+        try ctx.expectSentError(-31998, "UnknownTargetId", .{ .id = 10 });
+    }
+
+    {
+        try ctx.processMessage(.{ .id = 11, .method = "Target.getTargetInfo", .params = .{ .targetId = "TID-A" } });
+        try ctx.expectSentResult(.{
+            .targetInfo = .{
+                .targetId = "TID-A",
+                .type = "page",
+                .title = "",
+                .url = "",
+                .attached = true,
+                .canAccessOpener = false,
+            },
+        }, .{ .id = 11 });
+    }
+}