.Get() calls perform() on a list of infos, populating two shared maps. perform() now concurrently calls the ResourceActorFunc concurrently based on GVK, causing a data race condition in .Get()

This fixes that condition by locking the function to ensure these functions run serially for Helm 2 to fix the data race condition. This has since been optimized in Helm 3 so it's no longer an issue.
Signed-off-by: Matthew Fisher <matt.fisher@microsoft.com>