RelaxedSchema: allow additional properties

[JustinASmith]

Description:

Fixes RelaxedSchema to properly relax closed object schemas by dropping additionalProperties: false during deserialization.

This aligns relaxed schemas with their intended use for schema intersection and forward-compatible document validation.

Workflow steps:

(How does one use this feature, and how has it changed)

Documentation links affected:

(list any documentation links that you created, or existing ones that you've identified as needing updates, along with a brief description)

Notes for reviewers:

Unit tests pass and test:

• Test 1: Verifies that additionalProperties: false is removed during relaxation, ensuring relaxed schemas no longer enforce closed objects and accept unknown fields.
• Test 2: Confirms that additionalProperties: true is preserved, proving the relaxation does not alter schemas that explicitly allow arbitrary properties.
• Test 3: Ensures schema-valued additionalProperties is retained while its internal constraints are relaxed, maintaining structural intent without over-restricting validation.