Add LocationCachingProxy to add caching to location requests

[hughie-coles]

Here I am applying the proxy pattern to add caching to our location API calls. This will improve performance. The caching period is also configurable

[Kilo59]

Thanks for the PR.
The caching logic on this app has long been in need of a rework!

It may take me a bit to work through the PR but I'll try to do it soon.

[hughie-coles]

Honestly, I'm just doing these PRs as part of a class project, so no need to spend any effort on them