[C++] dim_names in Tensor and SparseTensor

[asfimport]

Along with ARROW-4388, it would be useful to introduce dim_names in Tensor and SparseTensor of C++ library.

Reporter: Kenta Murata / @mrkn
Assignee: Kenta Murata / @mrkn

Externally tracked issue: #3507

PRs and other links:

• GitHub Pull Request #3507

_{Note: This issue was originally created as ARROW-4397. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 3507
#3507