fix: pass appPath to the env from karma.conf.js

Two different webpack compilations are started on `tns test` command - the one from `karma-webpack` and the second one from `nativescript-dev-webpack`. As the karma's webpack doesn't provide appPath to the env and there is a hardcoded `appPath` inside `webpack.config.js` (to `src` for example), it works only with that hardcoded path.

Rel to: #5070

Author: Fatme

resources/test/karma.conf.js

@@ -99,6 +99,7 @@ function setWebpack(config, options) {
     const env = {};
     env[config.platform] = true;
     env.sourceMap = config.debugBrk;
+    env.appPath = config._NS && config._NS.options && config._NS.options.appDirectoryRelativePath;
     options.webpack = require('./webpack.config')(env);
     delete options.webpack.entry;
     delete options.webpack.output.libraryTarget;