Implement `squeeze` and `reshape`.

[1uc]

These methods allow reshaping the memory space. This can be used as an alternative to broadcasting.

Example:

Let dset be a dataset with shape [3, 1, 1]. Then,

dset.reshapeMemSpace({3}).read<std::vector<double>>();
dset.squeezeMemSpace({1, 2}).read<std::vector<double>>();

can be used to read into a one-dimensional dataset.

[1uc]

This is preparatory work to allow #992.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 83.75000% with 13 lines in your changes are missing coverage. Please review.

Project coverage is 86.26%. Comparing base (070badf) to head (1f09187). Report is 1 commits behind head on master.

Files	Patch %	Lines
src/examples/broadcasting_arrays.cpp	0.00%	9 Missing :warning:
include/highfive/bits/H5Attribute_misc.hpp	72.72%	3 Missing :warning:
include/highfive/bits/H5Slice_traits_misc.hpp	92.85%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #991 +/- ## ========================================== - Coverage 86.31% 86.26% -0.05% ========================================== Files 92 94 +2 Lines 5919 5986 +67 ========================================== + Hits 5109 5164 +55 - Misses 810 822 +12 ```

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