Add a search route for Service Desk

Test for a null value being provided to the search/epm route

Add a global search route that preforms an unrestricted search against the entire community

As a user, I want to be able to control the nature of my search results.

Right now, I can only search in the overall Endpoint Manager and Endpoint Security space. I want to be able to provide a subspace, like Inventory, for searching.

If an invalid space is provided, an ephemeral message should be returned to warn the user, and the search should default to the parent space.

As a user, I want to be able to specify what types of results to return, such as Document, Thread, Help Page, Readme, etc.

Test for invalid characters posted to the /search/epm route