fix: merge of TaskOptions and TaskOptions validator

[PierrePicard20]

Motivation

Some merging rules in TaskOptions were inverted and session's default TaskOptions validator should differ from task's TaskOptions validator.

Description

Fix the rules of merge of TaskOptions, and introduce a parameter in TaskOptions validator to differentiate sessions case from tasks case.

Testing

Added unit tests for TaskOptions validator

Impact

Fix merge of TaskOptions and TaskOptions validator

Additional Information

None

Checklist

• My code adheres to the coding and style guidelines of the project.
• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• I have thoroughly tested my modifications and added tests when necessary.
• Tests pass locally and in the CI.
• I have assessed the performance impact of my modifications.

[CLAassistant]

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