Add "Tween easing (text)" as a new parameter/property type for extension creators

[tristanbob]

Description

Tweens are a very powerful yet simple way to describe how an object changes over time.
A lot of extensions could leverage this power by letting users specify the Tween easing they want. Currently, this can only be done by the extension creator spending a long (and error-prone) process to add each easing.

Solution suggested

• [ ] Add "Tween easing (text)" as a new parameter/property type for extension creators.

Users would have the same experience when selecting the easing in the extension as they do when editing a tween.

[D8H]

If someone is facing this issue, a workaround is to close the project and open its json file with a text editor to copy paste the values.

This is a parameter with choices that can be copied:

                {
                  "codeOnly": false,
                  "defaultValue": "",
                  "description": "Easing",
                  "longDescription": "",
                  "name": "Easing",
                  "optional": false,
                  "supplementaryInformation": "[\"linear\",\"easeInQuad\",\"easeOutQuad\",\"easeInOutQuad\",\"easeInCubic\",\"easeOutCubic\",\"easeInOutCubic\",\"easeInQuart\",\"easeOutQuart\",\"easeInOutQuart\",\"easeInQuint\",\"easeOutQuint\",\"easeInOutQuint\",\"easeInOutSine\",\"easeInExpo\",\"easeOutExpo\",\"easeInOutExpo\",\"easeInCirc\",\"easeOutCirc\",\"easeInOutCirc\",\"easeOutBounce\",\"easeInBack\",\"easeOutBack\",\"easeInOutBack\",\"elastic\",\"swingFromTo\",\"swingFrom\",\"swingTo\",\"bounce\",\"bouncePast\",\"easeFromTo\",\"easeFrom\",\"easeTo\"]",
                  "type": "stringWithSelector"
                }

The parameter where choices must be pasted can be searched using its description.

[D8H]

What could be an issue when implementing this change request is that Tween is an extension and parameter types are defined in Core where tween concepts shouldn't be known.