[C++] track how much is spent in allocation for a given operation

[asfimport]

While profiling ARROW-16161, Memory allocation would sometimes appear to take up a few percent of total runtime. Especially the creating/copying of CPUMemoryManager objects seems to be more costly then then allocator calls themselves at times. It would be good to see how much different operations are affected by this (possibly even distinguish between time a Pool allocation and in the allocator itself).

Reporter: Tobias Zagorni / @zagto

_{Note: This issue was originally created as ARROW-16712. Please see the migration documentation for further details.}

[github-actions]

This issue has been marked as stale because it has had no activity in the past 365 days. Please remove the stale label or comment below, or this issue will be closed in 14 days. If this improvement is still desired but has no current owner, please add the 'Status: needs champion' label.