Improve flattening of results from pushAdapter

[flovilmart]

Better flattens the push adapter results for better handling of push status.

By default the push adapter should return a promise response for each push, and may have multiple senders, so arrays may not be flat

[codecov-io]

Current coverage is 93.06%

Merging #1204 into master will increase coverage by +0.04% as of 9a888c0

@@            master   #1204   diff @@
======================================
  Files           83      83       
  Stmts         5278    5281     +3
  Branches       963     963       
  Methods          0       0       
======================================
+ Hit           4910    4915     +5
  Partial         10      10       
+ Missed         358     356     -2

Review entire Coverage Diff as of 9a888c0

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