Add fast path for `concat` when the axes and partitioning is aligned (#818)
Add fast path for `concat` when the axes and partitioning is aligned (#818)

* Add fast path for `concat` when the axes and partitioning is aligned

* Resolves #817
* This is a common usecase, where the partitioning is already aligned
* Performance is improved significantly, operations that took O(10s) are taking 300ms
* Properly propagate metadata to further improve performance

* Lint

modin-project/modin,modin-project/modin