Add support for additional key/value pairs in X-MoneyTrace header

[HaloFour]

Adds support for additional unrecognized key/value pairs in the X-MoneyTrace header. The header will be considered value as long as it has at least 3 key/value pairs and that each of the trace-id,parent-id and span-id keys have been seen. Any other key/value pairs will be ignored.

See: #43
Comcast/money#158

[CLAassistant]

All committers have signed the CLA.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
1 Code Smell

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

Merging #44 into master will increase coverage by 1.52%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #44      +/-   ##
==========================================
+ Coverage   67.95%   69.48%   +1.52%     
==========================================
  Files           4        4              
  Lines         181      154      -27     
==========================================
- Hits          123      107      -16     
+ Misses         55       45      -10     
+ Partials        3        2       -1     

Impacted Files	Coverage Δ
trace.go	100.00% <100.00%> (ø)
span.go	90.47% <0.00%> (-1.02%)	⬇️
tracker.go	4.76% <0.00%> (-1.01%)	⬇️
spanner.go	89.28% <0.00%> (+4.43%)	⬆️

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