Minimize js bundle sizes

[jorg-vr]

This pull request tries to minimize the javascript bundle sizes. Duplicate dependencies are merged into a common bundle.

Momentjs is replaced by dayjs, which allows for proper treeshaking.

This pr also adds webpack-bundle-analyzer as dev dependency to analyze webpack bundles.

It also contains a small refactor to use the utility method for flatpickr. (Which is no longer relevant for this pr, but improves the code)

Old

Total unminimized js size 4.85Mb
Transfered size from naos:

• application_old 144KB
• application_pack 105.97KB
• vissualisations 94.58KB
• series 52.13kb
• description 40.5kb
• exercise 40.36kb
• submission 37.27kb
• course 24.49kb

New

Total unminimized size 1.8Mb
Transfered size from naos:

• commons 153.59 kb
• application_old 144kb
• application_pack 6.52kb
• series 17.8 kb
• vissualisations 9.02 kb
• submission 6.42 kb
• course 6.38 kb
• exercise 3.33 kb
• description 2.15kb

Todo in future prs:

• use webpack for old application file
• remove jquery

Closes #3667 .

[lgtm-com]

This pull request introduces 3 alerts when merging 9c7da8e into 923c1e2 - view on LGTM.com

new alerts:

• 3 for Unused variable, import, function or class

[lgtm-com]

This pull request introduces 3 alerts when merging f8b38f0 into 923c1e2 - view on LGTM.com

new alerts:

• 3 for Unused variable, import, function or class

[lgtm-com]

This pull request introduces 1 alert when merging 15d3e35 into 923c1e2 - view on LGTM.com

new alerts:

• 1 for Unused variable, import, function or class