Support for up-to-date jquery versions (3.7.1+ and 4.0.0-beta2+)

Problem/Motivation

For security reasons I’m required to update jQuery on all our sites to a version that doesn’t have known security issues. clientside_validation needs a few minor tweaks to work.

Steps to reproduce

Use jquery_update and update to the current jquery version (3.7.1). See that form submissions stop working because of JavaScript errors.

Proposed resolution

• Collect issues caused by removed/changed API calls
• Exchange them with their up-to-date alternatives

Remaining tasks

• Review the provided patch
• More testing

User interface changes

None

API changes

None

Data model changes

None