[C++] Add optional argument to ADD_ARROW_TEST CMake function to add unit test prefix

[asfimport]

We are already adding prefixes manually in the filenames (example: https://github.com/apache/arrow/tree/master/cpp/src/arrow/ipc). This can be a bit awkward at times. It may be useful to have an option like PREFIX "ipc-" or PREFIX "plasma-" to make the unit tests related to a project component easier to identify

Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm

_{Note: This issue was originally created as ARROW-2889. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
This was resolved in ARROW-3075