Preserve axes in `permutedims`

[jishnub]

The vector method is unnecessary, as the fallback Base method uses reshape, which will do the same.

For the other method: On master,

julia> F = Fill(2, (SOneTo(2), SOneTo(3)))
2×3 Fill{Int64, 2, Tuple{SOneTo{2}, SOneTo{3}}} with indices SOneTo(2)×SOneTo(3), with entries equal to 2

julia> permutedims(F)
3×2 Fill{Int64, 2, Tuple{SOneTo{3}, SOneTo{2}}} with indices SOneTo(3)×SOneTo(2), with entries equal to 2

julia> permutedims(F, (2,1))
3×2 Fill{Int64}, with entries equal to 2

In the second operation, the static axes are lost. After this PR, the axes are preserved:

julia> permutedims(F, (2,1))
3×2 Fill{Int64, 2, Tuple{SOneTo{3}, SOneTo{2}}} with indices SOneTo(3)×SOneTo(2), with entries equal to 2

To make this type-stable, we require aggressive constant propagation on the permutation tuple.

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[mtfishman]

@jishnub I just came across a need for this, can this be merged?