Add permission check for dashboard diff api route

* Fix Github OAuth not working with private organizations

* Update documentation

Only allow override permissions that is higher

Did a bad pointer comparison so extended the tests for duplicate permissions.

ref #10770

grammar fix, add dir, and remove redundant info

Using a mocked guardian instead and relies on the actual guardian tests for verifying
permission handling correctness

If a dashboard inherits permissions from a folder, don't allow same permission to be added
to the dashboard with a lower permission.
Add backend validation so that you cannot add same permission to folder/dashboard, for example
same user/team with different permissions

* Alerting: Fix OK state doesn't show up in Microsoft Teams

* Fix formatting

fix: changed react-grid-layout to use grafana fork to a commit before https://github.com/STRML/react-grid-layout/commit/15503084fb7b0af826427c8c0706901e5745a39f, this fixes all the panel movement bugs, fixes #10831

[doc] Fix extra alerting options in installation->configuration

It is the only js package that is installed directly from
GitHub - this changes it to download the tarball instead of doing a
git clone.

Background: Git clones against GitHub does currently does not work
with the container build which uses CentOS 6.6. It does not have support for
TLS 1.2 and cannot git clone against GitHub since they removed support for
TLS 1.0 and 1.1.

closes #11005

docs: update shortcut docs

Fix keyboard shortcuts

Snapshot fixes and changes to snapshot list