Remove restrictive patterns from packages/.gitignore to track all .meta files

Author: jdetter

sdks/csharp/packages/.gitignore

@@ -1,11 +0,0 @@
-# Ignore most of NuGet package structure, except DLLs which are required by Unity.
-/*/*/*
-
-!/*/*/analyzers
-!/*/*/analyzers.meta
-
-!/*/*/lib
-!/*/*/lib.meta
-
-# Ignore XML documentation metadata from packages too.
-*.xml