Introducing caching options

[manuel-watchenterprise]

The current flow is that the singleton service class is using class property as cache ("in-memory"), however, this can cause problems in background processes (incl. Horizon / Queue) and if the app is utilising Laravel Octane.

There are 3 options now:

• in memory caching (default, previous)
• using a configured cache store (e.g. Redis)
• no caching at all

I will have no time to add tests, really sorry. Feel free to close this PR if that's a problem and no one can add them.

Relates to #182 .