Fallout from aaf81a5

containers#1446

This is meant to make the project more searchable on the Internet.  More
and more people have been pointing out that "toolbox" is terribly
difficult to search for, and it's impossible to find any decent
Internet real estate by that name.

Some exceptions:

  * The code repository is still https://github.com/containers/toolbox.
    It will be renamed after giving a heads-up to other contributors.

  * The name of the binary is still 'toolbox'.  The name is embedded
    into existing Toolbx containers as their entry point, which is bind
    mounted from the host operating system when the containers are
    started.  Trivially renaming the binary will prevent these
    containers from starting.

  * For similar reasons, the TOOLBOX_PATH environment variable is still
    the same.

  * For similar reasons, the profile.d file to be read by the shell on
    start-up is still called toolbox.sh.

  * The label used to identify Toolbx containers and images is still
    called com.github.containers.toolbox.  There are many existing
    Toolbx containers, and many Toolbx images beyond the control of the
    Toolbx project that use this label to identity themselves.  Simply
    renaming the label will prevent these containers and images from
    being recognized.

  * The names of the built-in Toolbx images still retain the word
    'toolbox'.  Images under the new name need to be published on the
    OCI registries and the toolbox(1) binary needs to be taught to
    handle both old and new names, wherever necessary, for backwards
    compatibility.

  * The stamp file used to identify Toolbx containers is still called
    /run/.toolboxenv because it's used by various external programs and
    users to identify Toolbx containers.

  * The OSC 777 escape sequence to track and preserve the user's current
    Toolbx container [1] still emits 'toolbox' as the name of the
    container runtime.  Changing the escape sequence can break terminal
    emulation applications, like Prompt [2], that consume it.  Hence, it
    needs to be done carefully.

  * The runtime directories at /run/toolbox, when used as root, and
    $XDG_RUNTIME_DIR/toolbox, when used rootless, weren't renamed.

    When used as root, /run/toolbox is embedded into existing Toolbx
    containers as a bind mount from the host.  Trivially renaming the
    path will prevent these containers from starting.

    Secondly, both these paths are used to synchronize container
    start-up.  If the paths are trivially renamed, and the toolbox(1)
    binary is updated and used without stopping all existing containers,
    then it won't be able to enter containers that were already started.
    Strictly speaking, this scenario isn't supported, since updates are
    always expected to be "offline" [3].  However, it's worth noting
    because solving the previous problem might also address this.

  * The configuration file for RPM is still called
    /usr/lib/rpm/macros.d/macros.toolbox.

[1] https://gitlab.freedesktop.org/terminal-wg/specifications/-/issues/17

[2] https://gitlab.gnome.org/chergert/prompt

[3] https://www.freedesktop.org/software/systemd/man/latest/systemd.offline-updates.html

containers#1399