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

extensions/import/coverConfig.json

@@ -0,0 +1,20 @@
+{
+	"enabled": true,
+	"relativeSourcePath": "..",
+	"relativeCoverageDir": "../../coverage",
+	"ignorePatterns": [
+		"**/node_modules/**",
+		"**/test/**"
+	],
+	"includePid": false,
+	"reports": [
+		"cobertura",
+		"lcov",
+		"json"
+	],
+	"verbose": false,
+	"remapOptions": {
+		"basePath": "..",
+		"useAbsolutePaths": true
+	}
+}