[RFC] New `inactive-by-default:` project key

[mbolivar-nordic]

This issue tracks a potential extension to the manifest schema. It is not a proposal at this point, just a placeholder for discussion.

Proposed syntax:

manifest:
  projects:
    - name: foo
      inactive-by-default: <true|false>

Proposed semantics:

• if key is missing, no behavior changes
• if key is false, no behavior changes
• if key is true, new behavior applies to whether project is active or inactive

The new behavior that applies if and only if the key is true is:

• if manifest.project-filter applies to the project, it decides whether the project is active or inactive; inactive-by-default has no effect in this case
• otherwise, the project is inactive

This applies regardless of where the project is defined in the import hierarchy.

Concerns:

• this can no longer be overridden in an importing manifest, so users will always have to take explicit action to enable such projects
• in the case of zephyr/west.yml, west init + west update will not result in a manifest that can be resolved

[mbolivar-nordic]

Discussion among @carlescufi @tejlmand @aescolar @mbolivar-nordic :

Fact that this cannot be overridden in an importing manifest is a serious problem. E.g. in NCS we could not write a manifest that imports zephyr and makes bsim active by default.

[mbolivar-nordic]

Potential way forward, not vetted, just an RFC

manifest:
  projects:
    - name: zephyr
      import:
        name-allowlist:
          - bsim
          - ...
        activate:
          - bsim