[Dialog] Add a directive to simplify dialog interaction

#### Please describe the feature you would like to request.
A directive that accepts a TemplateRef and a dialog configuration object
When the button this directive is placed on is clicked a dialog containing that Template is created

#### What is the use-case or motivation for this proposal?
Allows users to interact with dialogs like other components - through their markup bindings. No need to use poorly understood _entry components_. Dialog templates are part of the component template; input and output bindings are fully accessible (as are pipes.)

The existing programmatic only approach feels like there is a lot of ceremony over creating dialogs - many of which would otherwise be simple components.

#### Is there anything else we should know?
I've stubbed out what the implementation might look like here. I've used a version of this in production for over a year now. I've also included 2 examples of usage.
https://github.com/adammedford/material2/blob/open-dialog-directive/src/lib/dialog/dialog-open-directive.ts

I will submit a PR if there is interest in this; this version is to just convey what I'm talking about. I didn't want to go through the effort of a full implementation and docs if nobody cares to use it.

Comienza leyendo la implementación propuesta en src/lib/dialog/dialog-open-directive.ts y revisando los dos ejemplos de uso enlazados. Compara ese enfoque con las APIs de diálogo existentes y determina el alcance necesario para la directiva, la configuración, la plantilla, el binding y la documentación. Se considera completado cuando haya una implementación acordada y ejemplos documentados, pero el issue no identifica pruebas ni un diseño establecido.

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