Page provider display behavior fails to find provider by id

When a page provider display element (ie table, list, ..) is inside a template (ie dom-if) it'll have the template instance as data host thus is fails to find the provider by id.

in _nxProviderChanged we are currently looking up the dataHost with

{ this.nxProvider = this.__dataHost ? this.__dataHost.$[nxProvider}

but when the data host is a template instance we should rely on

{this.__dataHost._methodHost}