Code refactoring for extension testing (#10529)

* Setting up tests on import extension

* -Added API wrappers for all the azdata and vscode APIs to make them easily mockable
-Added some unit tests for the import extension
-Some code logic separations

* -added code report for the import extension in ci

* Did some more code refractoring

* -Added json report generation

* updated vscodetestcoverage to latest version in import extension.

* -remove duplicate codecoverageConfig.json

scripts/test-extensions-unit.js

@@ -15,6 +15,7 @@ const extensionList = [
 	'azurecore',
 	'cms',
 	'dacpac',
+	'import',
 	'schema-compare',
 	//'mssql',
 	'notebook',