rust: Fix decoding of variable-length sequence values

[tony-iqlusion]

Also adds tests for decoding byte and string sequences

[codecov-io]

Codecov Report

Merging #86 into develop will increase coverage by 6.45%.
The diff coverage is 84%.

@@             Coverage Diff             @@
##           develop      #86      +/-   ##
===========================================
+ Coverage    72.83%   79.28%   +6.45%     
===========================================
  Files           14       14              
  Lines          600      618      +18     
===========================================
+ Hits           437      490      +53     
+ Misses         163      128      -35

Impacted Files	Coverage Δ
rust/src/decoder/sequence.rs	80.37% <84%> (+43.29%)	⬆️

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