* Refactor: initial commit

* Tests: updates tests

* Tests: updates snapshots

* Chore: updates after PR comments

* Chore: renamed initVariablesBatch

* Tests: adds transactionReducer tests

* Chore: updates after PR comments

* Refactor: renames cancelAllDataSourceRequests

* Refactor: reduces cancellation complexity

* Tests: adds tests for cancelAllInFlightRequests

* Tests: adds initVariablesTransaction tests

* Tests: adds tests for cleanUpVariables and cancelVariables

* Always cleanup dashboard on unmount, even if init is in progress. Check if init phase has changed after services init is completed

* fixed failing tests and added some more to test new scenario.

Co-authored-by: Torkel Ödegaard <torkel@grafana.com>
Co-authored-by: Marcus Andersson <marcus.andersson@grafana.com>