Add support for System database package references for SDK-style sql projects (#23309)

* add package reference type for system db references

* Add radio buttons

* hookup

* add test

* handle changing reference type radio buttons

* cleanup

* update strings

* change style to type

* change more places with style to type

* blank lines

extensions/types/vscode-mssql.d.ts

@@ -1406,6 +1406,11 @@ declare module 'vscode-mssql' {
 		MSDB = 1
 	}
 
+	export const enum SystemDbReferenceType {
+		ArtifactReference = 0,
+		PackageReference = 1
+	}
+
 	export interface DatabaseReference {
 		suppressMissingDependencies: boolean;
 		databaseVariableLiteralName?: string;