Msf::Config.install_root already existed, but I didn't know about it
until egypt pointed it out, so remove the new Msf.root and use
Msf::Config.install_root in the specs instead.
[Fixes#37630057]
Modules were always being detected as having file changes because the
parent_path directory, instead of the actual module_path, was being
passed to module_manager.file_changed?, which caused the modification
times to not match.
To ensure this change fixes the ambiguous module warnings, a full spec
for Msf::Core::Modules::Loader::Base has been written.
spec/msf has moved to spec/lib/msf to match conventional spec layout and
allow for the spec/support directory to not be confused as a lib
subdirectory being tested.