Use layout_getindex for adjoint-LayoutVectors with range access

[DanielVandH]

Before:

julia> using LazyArrays; v = ((1:10_000) .* LazyArrays.AccumulateAbstractVector(*, 1:10_000'))'; @time v[1:1, 1:10_000];
  0.031649 seconds (476.63 k allocations: 12.861 MiB)

After:

julia> using LazyArrays; v = ((1:10_000) .* LazyArrays.AccumulateAbstractVector(*, 1:10_000'))'; @time v[1:1, 1:10_000];
  0.000031 seconds (65 allocations: 2.156 KiB)

(Improved timings also require JuliaArrays/LazyArrays.jl#387)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.79%. Comparing base (b9b424e) to head (086fb29).
⚠️ Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #265      +/-   ##
==========================================
+ Coverage   89.52%   89.79%   +0.26%     
==========================================
  Files          11       11              
  Lines        1938     1950      +12     
==========================================
+ Hits         1735     1751      +16     
+ Misses        203      199       -4     

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