Bugfix/ls24004010/conversion to ds for unlimited string type

[GaetanoDiNatale]

Description

This work adds the ability to convert values of type UnlimitedStringType into a data structure during MOVEL operations.

Technical notes

To achieve the goal, data_definitions.kt was updated to handle UnlimitedStringType correctly, ensuring no modification or padding of unlimited strings.

Related to #LS24004010

Checklist:

• If this feature involves RPGLE fixes or improvements, they are well-described in the summary.
• There are tests for this feature.
• RPGLE code used for tests is easily understandable and includes comments that clarify the purpose of this feature.
• The code follows Kotlin conventions (run ./gradlew ktlintCheck).
• The code passes all tests (run ./gradlew check).
• Relevant documentation is included in the docs directory.

[lanarimarco]

Good work.
I just ask for a small additional effort by adding something to your test that helps me understand what happens when the content of £UIBME exceeds 4 characters.