Renaming variables throughout for clarity

[damonbayer]

Closes #156.

No changes to any of the model workings. Just renaming variables to make things easier to follow.

For example:

• objects named x_dist that are actually random variables are renamed x_rv
• object with vague names like latent are renamed to be more specific like latent_infections or latent_hosp_admissions
• predicted as a descriptor is replaced by observed or sampled where appropriate
• acronyms like ihr are replaced by more descriptive terms like infection_hosp_rate
• i0 is consistently formatted as I0

[codecov]

Codecov Report

Attention: Patch coverage is 97.10145% with 2 lines in your changes missing coverage. Please review.

Project coverage is 94.75%. Comparing base (df0b4d5) to head (53d778c).

Files	Patch %	Lines
model/src/pyrenew/latent/hospitaladmissions.py	95.23%	1 Missing ⚠️
model/src/pyrenew/model/admissionsmodel.py	95.23%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #179      +/-   ##
==========================================
- Coverage   94.77%   94.75%   -0.02%     
==========================================
  Files          39       39              
  Lines         842      839       -3     
==========================================
- Hits          798      795       -3     
  Misses         44       44              

Flag	Coverage Δ
unittests	94.75% <97.10%> (-0.02%)	⬇️

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[gvegayon]

Minor comment

[AFg6K7h4fhy2]

Looking good for the most part (see comments for flags and or suggestions).

[AFg6K7h4fhy2]

Another small remark regarding outdated use of typing.

[AFg6K7h4fhy2]

Everything looks good. See comment history.