DEVX-6461: Improving Exceptions for API Errors

[superchilled]

This PR:

• Adds additional context to some exception types.
  • It creates a new exception type Vonage::APIError from which Vonage::ClientError and Vonage::ServerError now inherit.
  • When an exception resulting from an API response not in the 2xx/3xx range, when the exception is raised the Net::HTTPResponse object is now made available as a property on the exception
  • Unit tests have been added/updated to cover the new functionality.

[codecov-commenter]

Codecov Report

Merging #287 (fc6470b) into main (44f2bb6) will decrease coverage by 0.03%.
The diff coverage is 94.87%.

❗ Current head fc6470b differs from pull request most recent head 5aadc81. Consider uploading reports for the commit 5aadc81 to get more accurate results

@@            Coverage Diff             @@
##             main     #287      +/-   ##
==========================================
- Coverage   97.96%   97.93%   -0.03%     
==========================================
  Files         107      108       +1     
  Lines        1967     1988      +21     
==========================================
+ Hits         1927     1947      +20     
- Misses         40       41       +1     

Files Changed	Coverage Δ
lib/vonage.rb	91.66% <ø> (ø)
lib/vonage/errors.rb	94.44% <88.23%> (-2.70%)	⬇️
lib/vonage/api_error.rb	100.00% <100.00%> (ø)
lib/vonage/client_error.rb	100.00% <100.00%> (ø)
lib/vonage/server_error.rb	100.00% <100.00%> (ø)

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