Switch from UglifyJs to Terser

[DimitarTachev]

Describe the solution you'd like
Terser is a fork of Uglify that retains the API and CLI compatibility. It shouldn’t really change the results, but it has more maintainers and fixes for a few long-standing issues with UglifyJS. Also, it's already used in Angular, Vue and React and we will unify the minification process in our Web + Mobile Code Sharing stories.

Additional context
webpack-contrib/terser-webpack-plugin#15
webpack/webpack#7923

[DimitarTachev]

Acceptance Criteria:

[ ] The uglified app size with Terser should be less or equel compared to the one with UglifyJs.
[ ] The uglified app build time with Terser should be less or equel compared to the one with UglifyJs.
[ ] The uglified app error stack traces should contain the proper line numbers based on the source maps (hidden or not).