importer-rest-api-specs - data workaround for AlertsManagement and move call to removeUnusedItems

[stephybun]

This PR

• Adds a data workaround for the ActionRules resource in AlertsManagement which will allow us to remove AlertsManagement entirely from the provider
• Moves where we call removeUnusedItems, this was previously called everytime we parsed data associated with a swagger tag, but this results in the removal of models that might need to referenced in data workarounds.
• removeUnusedItems is now called after all the processing has been done for a service
• Refactors removeUnusedItems to take separate constants and models argument instead of a result argument of type ParseResult
• Calls removeUnusedItems in the test helper used for parsing the testdata since it's no longer called iteratively in the parse function that we're testing. We still need to replicate the whole parsing process for these tests to be able to ensure the behaviour we're expecting is maintained

The effects of this on the existing API definitions is minimal, all of the changes listed below will not affect any resources in the provider

Changes not staged for commit:
  (use "git add/rm <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        deleted:    api-definitions/resource-manager/DataFactory/2018-06-01/DataFlowDebugSession/Constant-IntegrationRuntimeReferenceType.json
        deleted:    api-definitions/resource-manager/DataFactory/2018-06-01/DataFlows/Model-PowerQuerySink.json
        deleted:    api-definitions/resource-manager/DataFactory/2018-06-01/Pipelines/Model-DataFlowSink.json
        deleted:    api-definitions/resource-manager/DataMigration/2021-06-30/Commons/Model-MongoDbConnectionInfo.json

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        api-definitions/resource-manager/AlertsManagement/2019-05-05-preview/ActionRules/Constant-SuppressionType.json
        api-definitions/resource-manager/AlertsManagement/2019-05-05-preview/ActionRules/Model-ActionGroup.json
        api-definitions/resource-manager/AlertsManagement/2019-05-05-preview/ActionRules/Model-Diagnostics.json
        api-definitions/resource-manager/AlertsManagement/2019-05-05-preview/ActionRules/Model-Suppression.json
        api-definitions/resource-manager/AlertsManagement/2019-05-05-preview/ActionRules/Model-SuppressionConfig.json
        api-definitions/resource-manager/AlertsManagement/2019-05-05-preview/ActionRules/Model-SuppressionSchedule.json

[tombuildsstuff]

A few minor things but otherwise 👍