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.

No source file, test, or entry point is named in the issue. Start by reviewing the existing Material2 input implementation and the attached component concept, then define the enclosed field and desktop search-button behavior against the linked Material guidelines. Done should include an agreed implementation scope and verification of the resulting UI.

Written by the indexing model from the issue text.