[KOTLIN][CLIENT] Fix: Store parsed bool values in additionalProperties

[atomgomba]

Contents of Map<String, Object> additionalProperties are passed to the templates, but when these options are set via command-line this Map isn't updated.

For instance in Serializer.mustache.kt:105 the block will be incorrectly included in the output file even when --additional-properties=generateOneOfAnyOfWrappers=false was set on the command-line.

@jimschubert

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[atomgomba]

The CI is failing for some reason, but it seems to be unrelated to the changes made in this PR. Running the tests locally returns success:

[WARNING] Tests run: 3594, Failures: 0, Errors: 0, Skipped: 4