Add drop down for DYCE so can switch between dictation and search (discovery)

* Search for methods, classes, fields
* This would allow future functionality such as call hierarchy and tracing where a field is modified across methods

Start by locating DYCE's existing dictation and search entry points in the Eclipse plugin. Determine how searching methods, classes, and fields should coexist with dictation, and define the dropdown behavior before implementation. Done means users can switch between the two modes and the search scope is documented and testable.

Written by the indexing model from the issue text.