Fixing bugs for migration extension private preview 1. (#14872)

* Fixing Database backup page target layout

* Filtering out Azure sql db issues from assessment results
Correcting the database count for issued databases in sku rec page.

* Adding copy migration details button to migration status

* Adding start migration button to toolbar

* Fixing a syntax error in package.json

* Adding rg and location to target selection page
Filtering storage account by target location.

* Fixing dashboard title to azure sql migration

* Not making assessment targets selected by default.

* Adding tooltip for database and instance table items.

* Fixing duplicate task widget

* Some fixes mentioned in the PR
Localizing button text
renaming  a var
changing null to undefined.

* Adding enum for Migration target types

* Fixing a critical multi db migration bug because of unhandled race condition

* Adding Azure location api to azure core

* Adding source database info in status

extensions/azurecore/src/extension.ts

@@ -147,6 +147,11 @@ export async function activate(context: vscode.ExtensionContext): Promise<azurec
 				: azureResourceUtils.getSubscriptions(appContext, account, ignoreErrors);
 		},
 		getResourceGroups(account?: azdata.Account, subscription?: azureResource.AzureResourceSubscription, ignoreErrors?: boolean): Promise<azurecore.GetResourceGroupsResult> { return azureResourceUtils.getResourceGroups(appContext, account, subscription, ignoreErrors); },
+		getLocations(account?: azdata.Account,
+			subscription?: azureResource.AzureResourceSubscription,
+			ignoreErrors?: boolean): Promise<azurecore.GetLocationsResult> {
+			return azureResourceUtils.getLocations(appContext, account, subscription, ignoreErrors);
+		},
 		provideResources(): azureResource.IAzureResourceProvider[] {
 			const arcFeaturedEnabled = vscode.workspace.getConfiguration(constants.extensionConfigSectionName).get('enableArcFeatures');
 			const providers: azureResource.IAzureResourceProvider[] = [