chore: rework build script for release to get automatically the version

[tbozhikov]

As a summary for the script:
Use this script to pack .tgz for nativescript-angular package. The first passed param can be:

1. Path to .tgz file - in this case the script replaces the scoped dependency (@nativescript/angular) with it in the package.json file. Then packs.
2. Tag or exact version - in this case the script does npm install --save-exact to save the exact version (in case if tag). Then packs.
3. auto-version - this is interpreted by getting version from the scoped package.json file (nativescript-angular folder).