Disable check for $HOMEBREW_NO_RUBY_MACHO now that no alternative exists.

Flips HOMEBREW_RUBY_MACHO to HOMEBREW_NO_RUBY_MACHO.

Both the `CctoolsMachO` and `RubyMachO` module implement a common set of
methods that simplify querying `mach_data`. Move these into a shared
module, that gets included after either of these implementations is
loaded and included in `Pathname`.

- and branch for dylib_id_and_dylibs
- add branches for dylib id changing and change_install_name
- rename MachO module to HomebrewMachO to prevent namespace clashes
  with MachO in ruby-macho. this will eventually be replaced entirely
  with direct calls to ruby-macho methods
- break ruby-macho implementation out into separate RubyMachO module,
  and include either RubyMachO or CctoolsMachO (the original
  implementation) based on the HOMEBREW_RUBY_MACHO env var
- move ArchitectureListExtension and RubyMachO into separate files
- create {ruby_,cctools_,,}relocate.rb for isolation of different
  methods of mach-o relocation (ruby-macho vs. cctools)
- fill in require_install_name_tool? for ruby_relocate.rb
- rename {ruby_,cctools_,,}relocate.rb to keg, isolate requires in
  os/mac

Closes Homebrew/homebrew#45001.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>