Build application in sdk-nrf-toolchain docker image

[jangalda-nsc]

@gmarull regarding your comments to previous attempt:

1. Rework Zephyr build.yml instead of having 2 CI jobs - I believe it is better to keep 2 workflow files - using docker covers some cases, but customers may want to build their applications on Windows/Mac nodes or use some tools which are not available in ncs docker image.

2. Remove any hacks from the job (e.g. apt installs which can be part of the Docker image) - done

3. Use latest Docker image on main, only tag on releases. - we do not release latest tag for sdk-nrf-toolchain image at this moment. If such feature is added, I can change workflow file

Format commits as in NCS (nrf noup in this case) - done (I hope)

[gmarull]

lgtm, but this should be brought as a noup commit, and it should replace the existing job (we will only build using NCS docker image here)

[jangalda-nsc]

@gmarull PR is in the draft mode - I'm testing fixes in docker image and how they behave with GH action limitations. I'll make requested changes and convert to regular PR when it's ready for review.
Unfortunately, I can't temporary remove you from reviewers list since you are codeowners, so sorry for all spam messages with updates

[gmarull]

upstream workflow should be deleted as part of this commit (ncs specific workflow will replace the zephyr one)

[gmarull]

@gmarull regarding your comments to previous attempt:

1. Rework Zephyr build.yml instead of having 2 CI jobs - I believe it is better to keep 2 workflow files - using docker covers some cases, but customers may want to build their applications on Windows/Mac nodes or use some tools which are not available in ncs docker image.

The windows/mac builds are really GH windows/mac runners using the Zephyr SDK, so we test for free those environments using the recommended Zephyr setup. But since we're in NCS context, we should only build on what we officially support. So if we want to run on windows/mac then fine, but using the procedures we officially recommend. To me, it will be confusing for customers to understand which workflow to pick, as both do the same but, to build applications that use certain NCS features only NCS workflow will work fine. Now both work because ncs-example-application does not use any NCS feature that may require extra packages from NCS requirements.

[jangalda-nsc]

@gmarull I removed build.xml file to avoid confusion and resolved conflicts. I think, from maintenance point of view it will be easier to remove upstream workflow instead of replacing it. If there are any changes in upstream workflow, it will be more obvious that we should ignore them