build: move libcc patches to electron repo (#14104)

In the GN build, libchromiumcontent is no longer a distinct library, but
merely a container for a set of scripts and patches. Maintaining those
patches in a separate repository is tedious and error-prone, so merge
them into the main repo.

Once this is merged and GN is the default way to build Electron, the
libchromiumcontent repository can be archived.

patches/common/chromium/no_cache_storage_check.patch

@@ -0,0 +1,13 @@
+diff --git a/content/browser/cache_storage/cache_storage.cc b/content/browser/cache_storage/cache_storage.cc
+index ce6a21b..10a3b18 100644
+--- a/content/browser/cache_storage/cache_storage.cc
++++ b/content/browser/cache_storage/cache_storage.cc
+@@ -129,7 +129,7 @@ class CacheStorage::CacheLoader {
+         blob_context_(blob_context),
+         cache_storage_(cache_storage),
+         origin_(origin) {
+-    DCHECK(!origin_.unique());
++    // DCHECK(!origin_.unique());
+   }
+ 
+   virtual ~CacheLoader() {}