chore: use npm for all frontend dependencies

[dpgaspar]

Description

Use npm to manage all frontend dependencies.

Locally run:

npm install
npm run copy-files

bootstrap-datetimepicker as now moved to a maintained version

Note: this is changing some static locations

ADDITIONAL INFORMATION

• Has associated issue:
• Is CRUD MVC related.
• Is Auth, RBAC security related.
• Changes the security db schema.
• Introduces new feature
• Removes existing feature

[codecov]

Codecov Report

Merging #2144 (c26f557) into master (4db9a77) will decrease coverage by 33.51%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master    #2144       +/-   ##
===========================================
- Coverage   78.65%   45.15%   -33.51%     
===========================================
  Files          72       72               
  Lines        8695     8564      -131     
===========================================
- Hits         6839     3867     -2972     
- Misses       1856     4697     +2841     

Flag	Coverage Δ
python	45.15% <ø> (-33.51%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
flask_appbuilder/fieldwidgets.py	50.00% <ø> (-11.02%)	⬇️

... and 56 files with indirect coverage changes