Refactor static asset pipeline

[Gpetrak]

GeoNode includes many static libraries that seem outdated or unused and still uses Grunt, a bundler tool that is no longer commonly used.

Below are the sub-issues that need to be investigated and / or applied:

• Remove DEBUG_STATIC logic and unused JS libraries #13183
• Clean up the static/lib folder and remove Grunt-related scripts #13197
• Cleanup legacy code from static/geonode folder #13200
• Update the GeoNode's documentation according to the changes mentioned above