Fix parsing IDL oneway operations [21145]

[richiware]

Description

Currently the parser fails if it encounters a oneway operation. This PR fixes it.

Contributor Checklist

• Commit messages follow the project guidelines.
• N/A Tests that thoroughly check the new feature have been added/Regression tests checking the bug and its fix have been added; the added tests pass locally
• N/A Any new/modified methods have been properly documented.
• N/A Changes are backport compatible: they do NOT break ABI nor change library core behavior.
• N/A Changes are API compatible.
• N/A Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
• The title and description correctly express the PR's purpose.
• Check contributor checklist is correct.
• N/A Check CI results: changes do not issue any warning.
• N/A Check CI results: failing tests are unrelated with the changes.