feat(remote): Implement lazy distributed feature

[TwiN]

This is an experimental feature and it may be removed or updated in a breaking manner at any time. Use at your own risk.

Basically, all it does it retrieve the endpoint statuses from another remote host before returning the endpoint statuses. You may specify an endpoint prefix to prefix the name of all endpoints coming from a given remote instance with a string.

remote:
  instances:
    - endpoint-prefix: "myremoteinstance-"
      url: "https://status.example.org/api/v1/endpoints/statuses"

Relevant: #64

[codecov-commenter]

Codecov Report

Merging #307 (15e6107) into master (7daf2b5) will decrease coverage by 0.74%.
The diff coverage is 44.08%.

@@            Coverage Diff             @@
##           master     #307      +/-   ##
==========================================
- Coverage   84.58%   83.84%   -0.75%     
==========================================
  Files          54       54              
  Lines        3770     3812      +42     
==========================================
+ Hits         3189     3196       +7     
- Misses        449      480      +31     
- Partials      132      136       +4     

Impacted Files	Coverage Δ
client/client.go	73.07% <ø> (ø)
config/config.go	76.37% <22.22%> (-2.82%)	⬇️
controller/handler/endpoint_status.go	42.57% <40.84%> (-13.31%)	⬇️
controller/handler/handler.go	82.75% <66.66%> (ø)
controller/controller.go	95.45% <100.00%> (ø)

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