[C++] Add a Result<> returning method for for constructing a dictionary

[asfimport]

Dictionary types require a signed integer index type. Today there is a DCHECK that this is the case in the constructor.

When reading data from an unknown source it is possible due to corruption (or user error) that the dictionary index type is not signed. We should add a method that checks for signedness and use that at all system boundaries to validate input data.

Reporter: Micah Kornfield / @emkornfield
Assignee: Micah Kornfield / @emkornfield

Related issues:

• [C++] Fix crashes on corrupt IPC input (is fixed by)

_{Note: This issue was originally created as ARROW-9049. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
This was done in ARROW-7592.