Add error for cross pipeline dependencies

What does this MR do and why?

Fixes: undefined method 'pluck' for nil:NilClass: #349974 (closed)

This can happen in two scenarios (or more?), but they both happen when we have a config that uses the keyword dependencies.

Scenario 1 - if a dependency: job is from a job that is supposed to be in the same pipeline but is also referenced as a cross pipeline dependency (so we don't know what it is actually referring to):

jobA:
    script: echo "a"

jobB:
    script: echo "b"
    dependencies:
        - jobA
    needs:
        - job: jobA
          pipeline: other

Note: this can be fixed if the job: jobA is added to the needs

Scenario 2 - if a dependency: job is referring to a needs: job that is another pipeline.

jobA:
    script: echo "a"

jobB:
    script: echo "b"
    dependencies:
        - jobX
    needs:
        - job: jobX
          pipeline: other

In both cases, they should be using dependencies: job to refer to a job in the same pipeline.

The easiest way to validate this is by pasting the config above in the pipeline editor on main/master and with this branch.

Before	After
{"errors":[{"message":"Internal server error: undefined method pluck' for nil:NilClass"}]}`	"data":{"ciConfig":{"errors":["jobs:jobb dependencies must be from the same pipeline"],"mergedYaml":"---\njobX:\n script: echo \"a\"\njobB:\n script: echo \"b\"\n dependencies:\n - jobA\n needs:\n - job: jobA\n pipeline: other\n","status":"INVALID","stages":null,"__typename":"CiConfig"}}}

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