Broke out homescreen call to prevent back-to-back api calls

[fronzbot]

Description:

For implementations with no_prompt=True back-to-back API calls when looking for mini cameras caused a BlinkSetupError to be raised. These calls have been separated and this bug should be fixed now.

Checklist:

• Local tests with tox run successfully PR cannot be meged unless tests pass
• Changes tested locally to ensure platform still works as intended
• Tests added to verify new code works

[codecov]

Codecov Report

Merging #313 into dev will decrease coverage by 0.17%.
The diff coverage is 71.42%.

@@            Coverage Diff             @@
##              dev     #313      +/-   ##
==========================================
- Coverage   82.88%   82.70%   -0.18%     
==========================================
  Files           8        8              
  Lines         923      925       +2     
==========================================
  Hits          765      765              
- Misses        158      160       +2     

Flag	Coverage Δ
#unittests	82.70% <71.42%> (-0.18%)	⬇️

Impacted Files	Coverage Δ
blinkpy/blinkpy.py	79.09% <71.42%> (-0.73%)	⬇️

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