[Docker] Rename the jar / native executable

[AlexisSouquiere]

Describe the bug

When using kafkagen from a Gitlab CI pipeline in a script section, calling ./kafkagen doesn't work because the native executable is named application

To Reproduce

• Create a Gitlab CI pipeline with the following job

kafkagen:
  image: 
      name: michelin/kafkagen:1.2.0-native
  script:
    - kafkagen config get-contexts

Expected behavior

kafkagen command should be found

Environment (please complete the following information):

• Kafkagen docker image - version 1.2.0