scripts: build meta file workspace status extension

The PR #39382 raised a discussion on build reproducibility and knowledge
of west projects being out of sync with the west manifest.

Similar to how `git submodules` will report the working tree dirty if
any of the submodules HEAD points to a SHA different than the one
recorded in the super project.

Based on this discussion this commit extends the Zephyr build meta file
with overall workspace status included in the meta file.

It adds the following meta info to the build meta file:
> workspace:
>  dirty: false / true
>  extra: false / true
>  off:   false / true

A project using west and having an extra Zephyr module loaded not
controlled using git and a west project at a SHA different than the
SHA referenced by the manifest can look like:
zephyr:
  path: /.../zephyr
  revision: 863600cd
modules:
- name: mcuboot
  path: /.../bootloader/mcuboot
  revision: c61538748ead773ea75a551a7beee299228bdcaf
- name: local_module
  path: /.../local_module
  revision: null
west:
  manifest: /.../zephyr/west.yml
  projects:
  - path: /.../zephyr
    revision: 863600cd
  - path: /.../bootloader/mcuboot
    revision: c61538748ead773ea75a551a7beee299228bdcaf-off
  - path: /.../tools/net-tools
    revision: f49bd1354616fae4093bf36e5eaee43c51a55127
workspace:
  dirty: false
  extra: true
  'off': true

And without west:
zephyr:
  path: /.../zephyr
  revision: 863600cd
modules:
- name: hal_nordic
  path: /.../modules/hal/nordic
  revision: a6e5299041f152da5ae0ab17b2e44e088bb96d6d
- name: local_module
  path: /.../local_module
  revision: null
workspace:
  dirty: false
  extra: true

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>