Handle #file/#filePath distinction in Swift 5.3

[JensAyton]

Addresses this warning in Xcode 12 beta:

.../MobiusNimble/Test/TestUtil.swift:38:90: warning: Parameter 'file' with default argument '#file' passed to parameter 'file', whose default argument is '#filePath'
.../MobiusNimble/Test/TestUtil.swift:38:90: warning: note: did you mean for parameter 'file' to default to '#filePath'?

@jeppes

[codecov]

Codecov Report

Merging #167 into master will increase coverage by 0.17%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #167      +/-   ##
==========================================
+ Coverage   94.09%   94.26%   +0.17%     
==========================================
  Files          41       45       +4     
  Lines        1219     1256      +37     
==========================================
+ Hits         1147     1184      +37     
  Misses         72       72              

Flag	Coverage Δ
#ios	94.26% <ø> (+0.17%)	⬆️
#macspm	94.21% <ø> (+0.17%)	⬆️

Impacted Files	Coverage Δ
...ource/Deprecated/BlockingFunctionConnectable.swift	100.00% <0.00%> (ø)
...biusCore/Source/Deprecated/ActionConnectable.swift	100.00% <0.00%> (ø)
...iusCore/Source/Deprecated/ClosureConnectable.swift	100.00% <0.00%> (ø)
...usCore/Source/Deprecated/ConsumerConnectable.swift	100.00% <0.00%> (ø)

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