Error decoding

[wmcginty]

This PR creates an extension on JSONDecoder that handles DecodableContainer types. This makes it easier for custom errors to conform to DecodingFailureInitializable as they can use this extension in init(decodingError:data:).

Also cleaned up some formatting and tests.

[codecov-io]

Codecov Report

Merging #44 into release/2.0.0 will increase coverage by 0.24%.
The diff coverage is 100%.

@@               Coverage Diff                @@
##           release/2.0.0     #44      +/-   ##
================================================
+ Coverage          96.66%   96.9%   +0.24%     
================================================
  Files                 30      31       +1     
  Lines               1048    1065      +17     
================================================
+ Hits                1013    1032      +19     
+ Misses                35      33       -2

Impacted Files	Coverage Δ
Sources/Hyperspace/Extensions/URL+Additions.swift	100% <ø> (ø)	⬆️
Sources/Hyperspace/Request/AnyNetworkRequest.swift	100% <ø> (ø)	⬆️
...ces/Hyperspace/Request/Decoding/AnyDecodable.swift	97.91% <ø> (ø)
...ce/Extensions/JSONDecoder+DecodableContainer.swift	100% <100%> (ø)
Tests/DecodingTests.swift	94.7% <100%> (+0.14%)	⬆️
Sources/Hyperspace/Request/NetworkRequest.swift	100% <100%> (ø)	⬆️
.../Hyperspace/Request/URLQueryParameterEncoder.swift	100% <100%> (ø)	⬆️
...yperspace/Extensions/URLQueryItem+Extensions.swift	100% <100%> (+10%)	⬆️
Tests/NetworkActivityIndicatorTests.swift	100% <100%> (ø)	⬆️
...perspace/Request/Decoding/DecodableContainer.swift	100% <100%> (ø)
... and 2 more

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