bindings: add rust bindings

[ghost]

As we needed a binding for the swu client in Rust we created this simple prototype.
Maybe someone else could use it as well.
It works for us as is but could be extended if needed (e.g. with progress etc.).

[github-actions]

Contributing to SWUpdate

Contributions are welcome ! Please follow the following guideline for
contributions.

Contribution Checklist

These are mostly general recommendations and are common practice in a
lot of FOSS projects.

• use git to manage your changes [recomended]

• follow as much as possible kernel codestyle [recomended]
  Nevertheless, some rules are not so strict as in kernel. The maximum
  line length can be extended over 80 chars if this increase code
  readability.

• add the required copyright header to each new file introduced
  [required]

• • add signed-off to all patches [required]

    • to certify the "Developer's Certificate of Origin", see
      below
    • check with your employer when not working on your own!

• • add version number for your patches if follow-up versions are
    requested [recomended]

    • Add a "Change from Vx" description under the commit message
      to take track of the history of the patch.
    • It is suggested to use excellent "patman" tool to manage
      patches series. This is part of U-Boot's project
      (tools/patman), but it can be used in other projects, too.

• check that your patches do not break build [required]

  • There is a set of configuration files in the
    configs/ directory. Please run a
    build for all files in the directory to ensure that SWUpdate is
    still buildable from configurations different as yours.

• • post patches to mailing list [required]

    • use git format-patch to
      generate your patches.
    • use git send-email if
      possible. This avoid corruptions due to the mailers
    • add a prefix [meta-swupdate] if patches are intended to
      the Yocto's meta layer.
    • send patches inline, do not append them
    • no HTML emails!

• do not use github Pull Request. github facilities are not used for
  this project. The review is done in a single place : the Mailing
  List. PR from github are ignored.

Patches are tracked by patchwork (see
http://jk.ozlabs.org/projects/patchwork/). You can see the status of
your patches at http://patchwork.ozlabs.org/project/swupdate/list.

Developer's Certificate of Origin 1.1

When signing-off a patch for this project like this

Signed-off-by: Random J Developer <[email protected]>

using your real name (no pseudonyms or anonymous contributions), you
declare the following:

By making a contribution to this project, I certify that:

1. The contribution was created in whole or in part by me and I
   have the right to submit it under the open source license
   indicated in the file; or
2. The contribution is based upon previous work that, to the best
   of my knowledge, is covered under an appropriate open source
   license and I have the right under that license to submit that
   work with modifications, whether created in whole or in part by
   me, under the same open source license (unless I am permitted to
   submit under a different license), as indicated in the file; or
3. The contribution was provided directly to me by some other
   person who certified (a), (b) or (c) and I have not modified it.
4. I understand and agree that this project and the contribution
   are public and that a record of the contribution (including all
   personal information I submit with it, including my sign-off) is
   maintained indefinitely and may be redistributed consistent with
   this project or the open source license(s) involved.

[bgermann]

Would you mind stating that it is okay to use this under LGPL-2.1-or-later (libswupdate's license)? The default license is GPL-2.0-only, which your contribution would be under if you had used a Signed-off-by line. Please consider adding a SPDX license statement to each file to express the license. Without any of this, your contribution cannot be used by people who distribute their projects to other people (which will be any serious project).

When you have added the Signed-off-by, I am happy to forward this to the email list so it can be included in SWUpdate.