Feature/message attributes

[joe666]

This exposes the MessageAttributes which are different than the message Attributes when receiving messages

https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_Message.html

[codecov]

Codecov Report

Merging #46 (437e642) into master (89c7ffc) will decrease coverage by 4.03%.
The diff coverage is 71.42%.

@@ Coverage Diff @@ ## master #46 +/- ## ============================================ - Coverage 94.39% 90.35% -4.04%  - Complexity 139 141 +2  ============================================ Files 18 18 Lines 553 560 +7 ============================================ - Hits 522 506 -16  - Misses 31 54 +23 

Impacted Files	Coverage Δ	Complexity Δ
Service/Message.php	65.85% <66.66%> (-34.15%)	15.00 <2.00> (+2.00)	⬇️
Service/BaseQueue.php	90.80% <100.00%> (-9.20%)	26.00 <0.00> (ø)
DependencyInjection/Configuration.php	97.67% <0.00%> (-2.33%)	6.00% <0.00%> (ø%)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f1af721...437e642. Read the comment docs.