Fixes to test suite to support CUDA arrays

[gaurav-arya]

Implemented changes:

• A more generic construction of the random array in test_plan_adjoint
• An option to disable testing wrapper types (in our case, views), since we do not support them correctly when it comes to avoiding ambiguities with * (see Handling wrapper array inputs #119. I don't expect it to be solved in the immediate future, which is why I prefer to work around it for now).
• Tests correctness of fftdims as an iterable rather than its specific form, in accordance with the function contract.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (511d56b) 93.70% compared to head (2db1545) 93.73%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #118      +/-   ##
==========================================
+ Coverage   93.70%   93.73%   +0.02%     
==========================================
  Files           5        5              
  Lines         445      447       +2     
==========================================
+ Hits          417      419       +2     
  Misses         28       28              

Files	Coverage Δ
ext/AbstractFFTsTestExt.jl	100.00% <100.00%> (ø)
src/TestUtils.jl	50.00% <ø> (ø)

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[gaurav-arya]

Remove Random.rand! usage

[gaurav-arya]

Bump on review:) It should hopefully be an easy review, especially because this does not touch the core functionality, only the test utilities, which I have verified continue to work with FFTW and after this also with CUDA on JuliaGPU/CUDA.jl#2073

[gaurav-arya]

Bump

[gaurav-arya]

Bump on review. @devmotion raised in #118 (comment)) the issue of map not being contractually obligated to preserve the array type. But it does so in practice for all the cases I want to add these downstream tests, we didn't come up with a better solution, and we could easily improve the test suite with a backwards compatible solution in the future if that edge case does crop up.