pigweed.json: Exclude third_party from formatting

Also, replace tabs with spaces.

Change-Id: I614f2b338672b03bec870e1d71be7471d1565636
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/149011
Reviewed-by: Anthony DiGirolamo <tonymd@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>

pigweed.json

diff --git a/pigweed.json b/pigweed.json
index 1b07416..d4f41a2 100644
--- a/pigweed.json
+++ b/pigweed.json
@@ -2,26 +2,26 @@
   "pw": {
     "pw_cli": {
       "plugins": {
-	"presubmit": {
-	  "module": "pigweed_experimental_tools.presubmit_checks",
-	  "function": "main"
-	},
-	"heap-viewer": {
-	  "module": "pw_allocator.heap_viewer",
-	  "function": "main"
-	},
-	"ide": {
-	  "module": "pw_ide.__main__",
-	  "function": "main"
-	},
-	"rpc": {
-	  "module": "pw_system.console",
-	  "function": "main"
-	},
-	"package": {
-	  "module": "pigweed_experimental_tools.experimental_packages",
-	  "function": "main"
-	}
+        "presubmit": {
+          "module": "pigweed_experimental_tools.presubmit_checks",
+          "function": "main"
+        },
+        "heap-viewer": {
+          "module": "pw_allocator.heap_viewer",
+          "function": "main"
+        },
+        "ide": {
+          "module": "pw_ide.__main__",
+          "function": "main"
+        },
+        "rpc": {
+          "module": "pw_system.console",
+          "function": "main"
+        },
+        "package": {
+          "module": "pigweed_experimental_tools.experimental_packages",
+          "function": "main"
+        }
       }
     },
     "pw_env_setup": {
@@ -36,6 +36,13 @@
         ]
       },
       "gni_file": "build_overrides/pigweed_environment.gni"
+    },
+    "pw_presubmit": {
+      "format": {
+        "exclude": [
+          "\\bthird_party/"
+        ]
+      }
     }
   }
 }