refactor: bring common utils used accross the operators into one place

[jjmachan]

Description

This is to reduce duplication in the operators and I've moved some common utility functions from the operator into bentoctl.

The operators that use this approach

1. google-compute-engine
2. azure-container-instance
3. heroku
   closes:

[codecov]

Codecov Report

Merging #158 (26a83bf) into main (06547de) will decrease coverage by 4.98%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #158      +/-   ##
==========================================
- Coverage   65.37%   60.39%   -4.99%     
==========================================
  Files          19       24       +5     
  Lines        1031     1121      +90     
==========================================
+ Hits          674      677       +3     
- Misses        357      444      +87     

Flag	Coverage Δ
unit-tests	60.39% <0.00%> (-4.99%)	⬇️

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Impacted Files	Coverage Δ
bentoctl/utils/operator_helpers/__init__.py	0.00% <0.00%> (ø)
...ntoctl/utils/operator_helpers/create_deployable.py	0.00% <0.00%> (ø)
bentoctl/utils/operator_helpers/generate.py	0.00% <0.00%> (ø)
bentoctl/utils/operator_helpers/utils.py	0.00% <0.00%> (ø)
bentoctl/utils/operator_helpers/values.py	0.00% <0.00%> (ø)
bentoctl/exceptions.py	81.53% <0.00%> (+0.89%)	⬆️

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