Fix show for Fun in an ArraySpace

[jishnub]

This removes the show method for Fun{<:Union{ConstantSpace, ArraySpace{<:ConstantSpace}}}, as the special cases were becoming unwieldy to maintain

Fixes the display for

julia> D2 = Dirichlet(Chebyshev(),1);

julia> D2 * Fun()
Fun(ApproxFunBase.ArraySpace(ConstantSpace{Point{Float64}, Float64}[ConstantSpace(Point(-1.0)), ConstantSpace(Point(1.0))]), [1.0])

[codecov]

Codecov Report

Patch coverage: 57.14% and project coverage change: -0.10% ⚠️

Comparison is base (614f040) 27.62% compared to head (ff2e6d6) 27.53%.
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #556      +/-   ##
==========================================
- Coverage   27.62%   27.53%   -0.10%     
==========================================
  Files          80       80              
  Lines        8387     8379       -8     
==========================================
- Hits         2317     2307      -10     
- Misses       6070     6072       +2     

Files Changed	Coverage Δ
src/Operators/SubOperator.jl	42.64% <25.00%> (ø)
src/Operators/functionals/Evaluation.jl	43.47% <100.00%> (ø)
src/show.jl	62.96% <100.00%> (-3.42%)	⬇️

... and 1 file with indirect coverage changes

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