refactor consultation bed create and shift logic

[sainak]

Proposed Changes

• refactor and fix the conditions to check bed overlaps
• add more tests

Associated Issue

• fixes Beds can have conflicting records across patients care_fe#6161

Merge Checklist

• Tests added/fixed
• Update docs in /docs
• Linting Complete
• Any other necessary step

Only PR's with test cases included and passing lint and test pipelines will be reviewed

@coronasafe/care-backend-maintainers @coronasafe/care-backend-admins

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.35% 🎉

Comparison is base (b5e482c) 58.72% compared to head (1159f83) 59.08%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1577      +/-   ##
==========================================
+ Coverage   58.72%   59.08%   +0.35%     
==========================================
  Files         205      205              
  Lines       11136    11144       +8     
  Branches     1583     1587       +4     
==========================================
+ Hits         6540     6584      +44     
+ Misses       4387     4360      -27     
+ Partials      209      200       -9     

Files Changed	Coverage Δ
care/facility/api/serializers/bed.py	84.27% <100.00%> (+17.38%)	⬆️

... and 3 files with indirect coverage changes

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