Add method for determining service availability in a region

[marekaiv]

Issue #, if available:
n/a

Description of changes:
Generalize existing RegionConfiguration.is_sar_supported method into a is_service_supported method as we'll need to check availability of other services as well.

Description of how you validated changes:
Unit tests.

Checklist:

• Add/update unit tests using:
  • Correct values
  • Bad/wrong values (None, empty, wrong type, length, etc.)
  • Intrinsic Functions n/a
• Add/update integration tests -- covered by existing tests that use SAR
• make pr passes
• Update documentation n/a
• Verify transformed template deploys and application functions as expected n/a, low-level change

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Merging #2321 (7dd3301) into develop (e7a1496) will increase coverage by 0.89%.
The diff coverage is 98.20%.

@@             Coverage Diff             @@
##           develop    #2321      +/-   ##
===========================================
+ Coverage    93.58%   94.47%   +0.89%     
===========================================
  Files           90       97       +7     
  Lines         6124     7064     +940     
  Branches      1260     1435     +175     
===========================================
+ Hits          5731     6674     +943     
+ Misses         183      177       -6     
- Partials       210      213       +3     

Impacted Files	Coverage Δ
samtranslator/model/api/api_generator.py	94.38% <92.95%> (+0.02%)	⬆️
samtranslator/__init__.py	100.00% <100.00%> (ø)
samtranslator/feature_toggle/dialup.py	100.00% <100.00%> (ø)
samtranslator/feature_toggle/feature_toggle.py	100.00% <100.00%> (+12.16%)	⬆️
samtranslator/intrinsics/actions.py	98.78% <100.00%> (+0.06%)	⬆️
samtranslator/intrinsics/resource_refs.py	95.83% <100.00%> (-0.17%)	⬇️
samtranslator/metrics/method_decorator.py	100.00% <100.00%> (ø)
samtranslator/metrics/metrics.py	100.00% <100.00%> (ø)
samtranslator/model/__init__.py	97.63% <100.00%> (-0.02%)	⬇️
samtranslator/region_configuration.py	77.77% <0.00%> (-22.23%)	⬇️
... and 40 more

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[hawflau]

Approved. But we should be careful that get_available_regions might give false negative for some services even though they are actually available, as it depends on the data file in botocore.