Fix broadcaststyle for 0d FillArray

[jishnub]

Reland the 0d Fill fix from #215

After this,

julia> Broadcast.BroadcastStyle(typeof(Fill(4)))
Base.Broadcast.DefaultArrayStyle{0}()

and this method isn't being accidentally pirated by InfiniteArrays.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.45%. Comparing base (15c4030) to head (9d8e977).
Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
src/infarrays.jl	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #217      +/-   ##
==========================================
+ Coverage   89.37%   89.45%   +0.08%     
==========================================
  Files          10       10              
  Lines        1129     1138       +9     
==========================================
+ Hits         1009     1018       +9     
  Misses        120      120              

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