website: Update nav sidebar to take advantage of new terraform.io features
website: Update nav sidebar to take advantage of new terraform.io features

- Remove all the calls to `sidebar_current()` — no longer need it for activating
  the current sections.
- Default all data source and resource sub-sections to collapsed, since they can
  be opened dynamically now. (The guides section is small and important, so it
  can stay open if you'd like.)
- Add the optional "Expand/collapse all" control, which is useful if you need to
  cmd-F the entire list of resources.

Combined, these should make it a little easier to get around the AWS provider
pages.

kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,kjmkznr/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,Ninir/terraform-provider-aws,Ninir/terraform-provider-aws,terraform-providers/terraform-provider-aws,kjmkznr/terraform-provider-aws,Ninir/terraform-provider-aws,terraform-providers/terraform-provider-aws,Ninir/terraform-provider-aws