Allow for in-lined Sub-Model definitions in Property view:

Currently, when defining a property view:, you can use the factory_ format:
view: {
factory_: 'foam.ui.SomeView',
param1: value1,
...
}

But if you try to refer to this.something or some.package.CONSTANT then it doesn't work because 'this' isn't defined yet and the package may or may not be defined yet.

Instead, allow for the creation of in-lined models.

Ex.
view: {
extendsMode: 'foam.ui.SomeView',
properties: [ ... ]
}

Then, if it needs values from 'this', it can get them from the export/import features.