This commit improves the error message that is displayed when a user
specifies an unrecognized `bin/rails` command by offering "Did you
mean?" suggestions.  The suggestions cover all visible commands, and
supersede any incomplete (Rake-task-only) suggestions that Rake might
display.

__Before (example)__

  ```console
  $ bin/rails credentails:edit
  rails aborted!
  Don't know how to build task 'credentails:edit' (See the list of available tasks with `rails --tasks`)

  (See full trace by running task with --trace)

  $ bin/rails --tasks
  ...
  rails cache_digests:dependencies         # Lookup first-level dependencies for TEMPLATE (like messages/show or comments/_comment.html)
  rails cache_digests:nested_dependencies  # Lookup nested dependencies for TEMPLATE (like messages/show or comments/_comment.html)
  rails db:create                          # Creates the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use ...
  rails db:drop                            # Drops the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db...
  ...

  $ bin/rails credentails -h
  # no output

  $ bin/rails credentials -h
  # no output

  $ bin/rails versoin
  rails aborted!
  Don't know how to build task 'versoin' (See the list of available tasks with `rails --tasks`)
  Did you mean?  db:version

  (See full trace by running task with --trace)
  ```

__After (example)__

  ```console
  $ bin/rails credentails:edit
  Unrecognized command "credentails:edit" (Rails::Command::UnrecognizedCommandError)
  Did you mean?  credentials:edit

  $ bin/rails credentails -h
  Unrecognized command "credentails" (Rails::Command::UnrecognizedCommandError)
  Did you mean?  credentials:diff

  $ bin/rails credentials -h
  Unrecognized command "credentials" (Rails::Command::UnrecognizedCommandError)
  Did you mean?  credentials:diff

  $ bin/rails versoin
  Unrecognized command "versoin" (Rails::Command::UnrecognizedCommandError)
  Did you mean?  version
  ```