Proposal: Add an enclosed input variant aka Solo fields

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

#### What is the use-case or motivation for changing an existing behavior?
Input on Material2 does not currently support a [Solo Field](https://material.io/archive/guidelines/components/text-fields.html#text-fields-field-variations) which is currently in the Material Guidelines.

When a text field is used for a single action such as search, the text field may be elevated, with associated icons placed within it. An input line is not required.

On desktop, a raised search button should appear to the right of the search field.

I have attached a component I am working on currently.

Nell’issue non vengono indicati alcun file sorgente, test o punto di ingresso. Inizia esaminando l’implementazione esistente dell’input Material2 e il concept del componente allegato, quindi definisci il comportamento del campo delimitato e del pulsante di ricerca desktop in base alle linee guida Material collegate. Done dovrebbe includere un ambito di implementazione concordato e la verifica dell’UI risultante.

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