Reduce strtolower() calls in container get()

Problem/Motivation

The container does a strtolower() for every service name that's passed to it.

Proposed resolution

There's already an optimisation in there via an upstream PR I did to avoid this when the service has already been initialized, but I'm still seeing 190 calls to strtolower() that are completely useless. Just needs slight re-organisation of the code to avoid calling it at all.

This is not an exciting performance improvement - on my local we save about 0.5ms - but it will get worse the more container::get() calls there are for different services, and it's a free saving.

Before:

After:

Remaining tasks

Upstream PR.

API changes