Support conversion to JenkinsFile

In eclipse-simrel/simrel.build#815 (comment) @emerks very strongly recommends the use of JenkinsFile / pipeline.

How? Googling suggests that there could be a "Convert" option. I cannot see it. Googling again suggests that a conversion plugin is required.

Please make the appropriate facilities available to MoDisco, OCL, QVTd, QVTo JIPPs.

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More generally if/since JenkinsFile is the only professional way to work, please make it available to all JIPPs as standard and publicize a write up on how Eclipse JIPP users should evolve their work.