fix(actions): return all outputs of an action as a json string

[twelvemo]

What this PR does / why we need it:

To make it possible to return all outputs from actions as a json string, we need to allow setting the needsExecutedOutputs to true.

When referencing ${actions.deploy.<name>.outputs} without another key outputKey is undefined which without the change in this PR will cause needsExecutedOutputs to be false. This results in ${actions.deploy.<name>.outputs} to always be an empty object.

Which issue(s) this PR fixes:

Fixes #6046

Special notes for your reviewer:
TODO:

• Need to adjust the joi schema for outputs, so this is also documented in the reference docs.
• Need to track down why provider outputs are returned as plain object, while action outputs are returned as json string.