operationId: Allow getting only the method name

Created by: ygalblum

This PR adds the functionality I requested in #9719 (closed)

Add new configuration flags: REMOVE_OPERATION_ID_PREFIX_DELIMITER and REMOVE_OPERATION_ID_PREFIX_COUNT Add the corresponding fields in the DefaultCodegen Sanitize the operationId according to the new fields Add delimiter to list of nonNameElementPattern Add unit test for different cases (different delimiters and counts)

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fixes #9719 (closed)