Provide AADL Search that includes Plugin Contributions

[philip-alldredge]

It is often helpful to search the entire workspace for a text string using OSATE's/Eclipse's search feature. Search->File... In previous versions this would search the entire workspace. However, this capability no longer searches plugin contributions.
child of #1371

[lwrage]

It would be even better to have an AADL search dialog.

[lwrage]

An example for a search contribution: https://github.com/Pontesegger/codeandme/tree/master/search_provider/com.codeandme.searchprovider