convert unscoped enums to scoped enums

[stonecoldhughes]

Enumerations in this codebase appear to be unscoped; thus, they are "weakly typed". Scoped enumerations, in contrast, are "strongly typed". This may or may not be desired depending on how these enumerations are used.

scoped/unscoped enum reference: https://en.cppreference.com/w/cpp/language/enum

A brief treatment of strong vs weak typing.

https://en.wikipedia.org/wiki/Strong_and_weak_typing

[pelesh]

Closing for now. If there is a specific action recommended here we can reopen.