The univerally used exception types Out_of_ram, Out_of_caps, and Denied
used to be defined at quota_guard.h and ram_allocator.h whereas the
types are broadly used. This patch gathers those type definitions at
the central place exception.h instead, to gradually untangle the reliance
on exceptions, i.e., in quota_goard.h, and to make the output of error
messages printing exception types ('abort') more concise.
Issue #5245
2e76f4fc58