validation: feat(Validation): Add validation-object-errors binding (with new propertyNames parameter for ensureObject().satisfies())

Proposed Change

I have previously proposed adding a propertyNames parameter to ensureObject().satisfies() (see here) and here.

Further to that, I here propose the following:

Create a new binding like validation-errors called validation-object-errors for instance-level (rather than property-level) validation.

This new binding would have the following effects:

1. it would change behavior of the inner validate binding by causing whole object to be validated on each property change (rather than a single modified property).

2. in the ValidationRenderer, RenderInstruction would be filled-in with elements and property names for all the rules that have failed. (Again, see my earlier proposal and here.

(https://github.com/aurelia/validation/issues/279#issuecomment-250188672) that would come in quite handy here).

Use Case

My form contains a table of rows, each of which displays an object instance that has been added to the controller for validation.

I am validating at the object level, thus must manually call ValidationController.validate(). I want to display validation errors separately for each row and thus want an easy way to identify errors associated with each object.

Each object contains object rules (defined by ensureObject().satisfies()). These object rules do not depend on other rules, but they do relate to a set of properties on the object. However, unlike with ensure().satisfies() it is not possible to associate ensureObject().satisfies() with a property name, much less with multiple property names.

Further, I am using neither the validate binding nor a ValidationRenderer. Again, I am manually calling ValidationController.validate(), and manually rendering the error information when validate completes.

A ValidationRenderer could be useful for me in this scenario, but it is not, for the following reasons:

1. without using the validate binding, it does not provide the element(s) with which a property is associated.
2. it provides neither property names nor elements for rules define by ensureObject().satisfies()