Implement passing ENV variables from dependent jobs

What does this MR do?

Related to: #22638 (closed)

With help of DotEnv Variables Support, we can easily inherit env variables of dependent jobs.

With this MR, a job will inherit all Ci::JobVariables of dependencies if they are sourced with dotenv.

It will be enabled with FF ci_dependency_variables. (and will be deleted with a follow-up issue)

NOTE:

The implementation is different than Technical proposal of the issue.

Example

build:
  stage: build
  script:
    - echo "BUILD_VERSION=hello" >> build.env
  artifacts:
    reports:
      dotenv: build.env

deploy:
  stage: deploy
  script:
    - echo $BUILD_VERSION
  dependencies:
    - build

Screenshots

gitlab-ci.yml

Pipeline

Job: test

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team