Optimize performance of the app by means of JS minification and enabling GZIP compression

[commjoen]

What kind of changes does this PR include?

• Fixes or refactors
• A new challenge
• Additional documentation
• Something else: added GZIP encryption and better javascript minification

Description

Relates #762

Before performance: https://pagespeed.web.dev/analysis/https-arcane-scrubland-42646-herokuapp-com/sk5nlkefgz?form_factor=mobile
After performance: https://pagespeed.web.dev/analysis/https-arcane-scrubland-42646-herokuapp-com/5onoy8dvet?form_factor=mobile

Checklist:

• All the contributions made are solely the work of me and my co-authors
• I tested the changes in this PR (if applicable)
• I added unit tests to ensure my change works (when change in Java or on front-end code)
• The PR passes pre-commit hooks and automated tests