Refactored scheduler out of the service singleton provider

[Skarlso]

No description provided.

[Skarlso]

@michelvocks Bask in this beauty! :)) Arguably, the naming could be better, also, I'm thinking of creating some more folders in order to separate the provider and the services better.

However, this works ( I can now see that some of the tests failed, although locally everything ran... grrr. EDIT: Oh right.. The worker tests...:D ). It makes the tests a heck of a lot more stable because you don't have to worry about the fact that something overwrites your mock.

Eventually, if you like this way, I would like to refactor the rest of the singletons as well into services and providers.

[codecov-io]

Codecov Report

Merging #237 into master will increase coverage by 2.18%.
The diff coverage is 82.25%.

@@            Coverage Diff             @@
##           master     #237      +/-   ##
==========================================
+ Coverage   60.64%   62.82%   +2.18%     
==========================================
  Files          49       48       -1     
  Lines        4304     3844     -460     
==========================================
- Hits         2610     2415     -195     
+ Misses       1241     1028     -213     
+ Partials      453      401      -52     

Impacted Files	Coverage Δ
services/service_provider.go	72.54% <ø> (-2.06%)	⬇️
workers/scheduler/gaiascheduler/create_cmd.go	60.81% <0.00%> (ø)
workers/scheduler/gaiascheduler/workload.go	100.00% <ø> (ø)
workers/pipeline/ticker.go	47.13% <10.00%> (-1.26%)	⬇️
handlers/handler.go	90.41% <100.00%> (+1.01%)	⬆️
handlers/service.go	100.00% <100.00%> (ø)
workers/agent/agent.go	50.72% <100.00%> (+0.11%)	⬆️
workers/pipeline/create_pipeline.go	42.55% <100.00%> (-0.61%)	⬇️
workers/pipeline/service.go	100.00% <100.00%> (ø)
workers/scheduler/gaiascheduler/scheduler.go	59.77% <100.00%> (ø)
... and 2 more

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[Skarlso]

After master merge this isn't scheduling properly... hm 🤔

[Skarlso]

This is now working, however I need to do some exhaustive testing around triggering, agent, docker runners and remote workers as well.

[Skarlso]

Tested remote worker: ✅
Docker agent: ✅
Multiple workers with different assigned pipelines: ✅
Crontab: ✅