Add first Zephyr example

[arnopo]

Install environment for zephyr examples by:

1. porting the samples/subsys/ipc/openamp_rsc_table sample
2. updating it to be able to replay the https://github.com/OpenAMP/openamp-system-reference/wiki/Samples-and-demos on the stm32mp157F-dK2 board

[edmooring]

Not being a Zephyr expert, this is a less than substantive review.

[edmooring]

Looks good to go.

[tnmysh]

Looks good to me.

[wmamills]

I will provide suggested changes later today.
There are two main ones in the west manifest.

• use main as the revision to avoid bumps every day
• (We can have a different manifest for release tags)
• rename openamp-zephyr-staging to zephyr on clone to keep the west usage simple

[wmamills]

I double checked and the only thing I modified was the manifest. What I have looks like this at the end:

  projects:
    - name: openamp-zephyr-staging
      path: zephyr
      revision: main
      import: true

With these changes you can change the readme to eliminate the -z openamp-zephyr-staging from the west command line.

[arnopo]

I will provide suggested changes later today. There are two main ones in the west manifest.

• use main as the revision to avoid bumps every day

This means that we would have to set the main branch of the on top of the Zephyr revision we want to use, to be aligned with a release. Or do you propose that we use the main branch of the zephyr main repo?

• (We can have a different manifest for release tags)

• rename openamp-zephyr-staging to zephyr on clone to keep the west usage simple

Right that would simplify the use, I will test it