Feature request: code search

There are several things that the VSTS web application search does not support (and a lot that it does). Would be great if the CLI supported search, with or without features not currently supported on the site (date filtering, author filtering).

The issue names no files, tests, or command entry point. Start by locating the Azure CLI extension's existing command structure and how it interacts with Azure DevOps code search; clarify whether basic search and date or author filtering are required. Done means the CLI provides a defined code-search command with the agreed scope.

Written by the indexing model from the issue text.