Additional tests for import extension (#10953)

* 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

* changes code coverage to 36%

* adding some comments

* Removing unnecessary exports

* -refactored test code to replicate src structure
-some changes mentioned in the pr

* removed unnecessary prefixes from test case name

extensions/import/coverConfig.json

@@ -4,7 +4,8 @@
 	"relativeCoverageDir": "../../coverage",
 	"ignorePatterns": [
 		"**/node_modules/**",
-		"**/test/**"
+		"**/test/**",
+		"**/apiWrapper.js"
 	],
 	"includePid": false,
 	"reports": [