We should get @gozala's input here, I figure there are many options, and runtime lookups is both required (in the case where one is developing their add-on, by linking their addon folder to the firefox profile's `extensions` folder).  From here we have some options on how to optimize the add-on when `cfx xpi` is used.  For instance `cfx xpi` could generate and include a `harness-options.json` file which defines all of the mappings.  Another option is to include the mapping information in  the `package.json` file when `cfx xpi` is run, or yet another option is to cache the runtime generate mappings in the firefox profile directory someplace.

I'd like to get the runtime search completed first since it is required, then measure that against another options however.