Improving unregistering metafields in metaforms.js

[SamBauwensPM]

Description

Added the ability to unregister meta fields by name, templateUrl or a custom search predicate callback

We originally did that in a custom module of ours, and @EugeneOkhriemnko suggested I create a PR here so everyone can benefit.

Since there is no real method overloading in js, I did some _.isFunction magic to allow the same method ~group to accept the 3 different types of values for metaFieldToFind: name, function callback or object reference.

I added an error message because I think it's better t have an error than to silently not remove a field, but that could be considered a breaking change since the previous code didn't throw an error, if preferred this could be changed so that it only throws on error if metaFieldDescription, or not throw at all, or having this error throwing behaviour configured somewhere I don't know.

I tried to stay backwards compatible with the way unregisterMetaFields worked before, i.e it accepts an object reference in metaFieldToFind.

References

Sorry I have no idea what to put in this section.

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[vc-ci]

Reveiw task created: https://virtocommerce.atlassian.net/browse/VCST-1448