fix: execute bundle-config-loader only for the entry point of the application

[Fatme]

Currently bundle-config-loader is executed for any file of the application with the same name as main entry file. For example if the javascript application has app.js file located in ./app/some-folder/app.js, the bundle-config-loader will be executed for this file.

PR Checklist

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• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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• All existing tests are passing: https://github.com/NativeScript/nativescript-dev-webpack/blob/master/CONTRIBUTING.md#testing-locally-by-running-e2e-tests
• Tests for the changes are included.

What is the current behavior?

bundle-config-loader is executed for any file of the application with the same name as main entry file

What is the new behavior?

bundle-config-loader is executed only for the entry point of the application

Fixes/Implements/Closes #[Issue Number].

[Fatme]

test package_version#latest

[Fatme]

test package_version#latest