Webui default search does not scale

Refreshing the results every time a new character is entered in the fulltext field is incredibly costly when you have millions of documents in the repository. As a user you have to wait a long time to get your results.

It also makes it impossible to get search analytics because the top searches are more or less the 26 letters of the alphabet (edited)

Proposed resolution
On <nuxeo-input>, for default, asset and expired searches, only fire search (when in auto mode) with "enter" key pressed or focus is lost (see comments).

Implementation
Remove auto search behavior for fulltext search in following search forms:

• default
• expired
• assets
• trash