fix(ember): keep route hook context when performance-wrapping

[alexlafroscia]

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While integrating the Route Performance Tracking feature of @sentry/ember into my app, I ended up hitting a bunch of errors. It turns out that when wrapping the different Route functions that are performance-tracked, the context of the function is lost. This means that accessing this inside those methods -- a very common Ember pattern for accessing injected services -- breaks.

The existing tests don't cover this case because none of the routes in the dummy app that have the instrumentation wrapping access the context of the route.

I started by adding the unit test in this PR, which failed, then updated the instrumentation method definition to make things pass again 🎉

With this change the context of these methods are preserved.

[alexlafroscia]

cc: @k-fish -- maybe you could take a look at this? Since I believe you have some context on the Ember integration.

[k-fish]

Yeah that looks good, and thanks for adding tests the dummy app doesn't cover. 👍

[alexlafroscia]

Wonderful! I'm excited to see this land so I can use these better insights in our Ember app