[#36737359]
Refactor the behavior of loading symbolic modules from cache by renaming
methods so it's clearer what they do and ensure that cached modules from
Fastlibs and directories can both be loaded, which was not previously
possible since the demand_load_module only called load_module_from_file.
Changed lexical scope when I changed the declaration from module Msf;
class ModuleSet to class Msf::ModuleSet so that constants in Msf would
not automatically resolve.
[Fixes#36737359]
Refactor Msf::ModuleManager into concerns so its easier to understand and
duplicate code can be made DRY. The refactoring also ensures that when
loading from directories, Fastlibs, or reloading, the wrapper module will
always be named so that activesupport/dependencies will function.