Replace a bunch of references to .packages

Most of these arguments are flowing through to a `--packages` argument
which allows passing the `package_config.json` file. In the long term we
should remove the `.packages` file entirely.

TEST=None, the change should have no visible impact.

Change-Id: I60a8b175d5e217a85588bbcb91cc5095514066b4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/211503
Auto-Submit: Nate Bosch <nbosch@google.com>
Commit-Queue: Nate Bosch <nbosch@google.com>
Reviewed-by: Kevin Moore <kevmoo@google.com>
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>

utils/dartanalyzer/BUILD.gn

@@ -40,7 +40,7 @@ prebuilt_dart_action("generate_summary_strong") {
     "../../sdk:write_version_file",
   ]
   script = "../../pkg/analyzer/tool/summary/build_sdk_summaries.dart"
-  packages = "../../.packages"
+  packages = "../../.dart_tool/package_config.json"
   output = "$root_gen_dir/strong.sum"
   outputs = [ output ]
   vm_args = [ "-Dsdk_hash=$sdk_hash" ]