Form-related fixes, improvements and refactoring

[DingDongSoLong4]

This started out as a fix for #4268, but I got a bit carried away...

• Fixed another validateDOMNesting error (<CommonLinkComponent> already adds a <Link>)
• Fixed a forwardRef error - <ReactDatePicker> requires its customInput to be "ref-able"
• Fixed the "encoding_image" intl message - the correct id is "actions.encoding_image"
• RatingSystem now returns null rather than undefined when clearing the rating value - this fits better when using it as a form input, since null represents clearing a value in GraphQL whereas undefined represents not modifying the existing value.
• Improved TextUtils.secondsToTimestamp() to properly support inputs over 24 hours and negative inputs. Since DurationUtils.secondsToString() is functionally equivalent to TextUtils.secondsToTimestamp(), I've removed the former and also moved DurationUtils.stringToSeconds() into TextUtils to be able to remove DurationUtils entirely.
• DurationInput also now returns null for the same reasons as RatingSystem, and it can now properly handle negative inputs, due to the above improvements to TextUtils.secondsToTimestamp().
• A minor change to DateInput, to no longer accept undefined as a value. The DateInput component is basically just a thin wrapper around an <input>, which should not have its value set to undefined unless it is uncontrolled.
• Removed a whole bunch of unused render functions in src/utils.
• The biggest change, refactored the rendering of the various edit forms. This means that all normal <input>-based components now have error messages displayed, and alignment and styling is more consistent across the different forms. The forms are also now much easier to use when on mobile: the inputs now always wrap so that the label is above the input on small screens, which allows the input to be wider.
• And then the actual fix for [Bug Report] performer height In centimeters with decimals causes Error Response not successful: Received status code 422 #4268 - fractional values are now truncated to integers when submitting the form. I've also done some refactoring in the yup schemas, and added utility functions for dealing with enums and numbers in forms.

Fixes #4268