[Table] Add inline editing for inputs

#### Bug, feature request, or proposal:

Feature request

#### What is the expected behavior?

Clicking on a text field should launch a simple edit dialog with an `md-input`. Hitting Enter would then close the dialog and save the input as the new value for the text field.

#### What is the use-case or motivation for changing an existing behavior?

This behavior is described in the Data Table section of the Material spec, found [here](https://material.io/guidelines/components/data-tables.html#data-tables-interaction), and would be useful to have as its own component.

#### Is there anything else we should know?

Accessibility is a real concern here, and there doesn't seem to be much discussion/affordance defined in the spec for possible solutions. The text field itself could be defined as a button with `aria-role="button"`, but that may be deceptive.

cc @andrewseguin @jelbourn

Inizia esaminando l’interazione richiesta e la specifica Material collegata per le tabelle di dati. Definisci l’approccio all’accessibilità prima di identificare i punti di ingresso pertinenti della tabella e dell’input; il lavoro è completato quando i campi di testo aprono una finestra di dialogo di modifica, Enter salva il nuovo valore e la chiude e l’interazione è accessibile.

Scritto dal modello di indicizzazione a partire dal testo della issue.