[Build] Add Jenkins pipeline to improve release preparation automation

This introduces a new Jenkins job named `Prepare Next Development Cycle`
that carries out many of the preparation tasks and aims to further
enhance the release preparation automation. This includes
- Updating the version of the Maven parent, all references to it and the
Eclipse products
- Updating the release version across build scripts
- Updating the previous release version to the current Release-Candidate

These tasks are currently done partly manually and partly automatically,
but through a mixture of the (hidden) Jenkins job to create-milestones
and distributed GH workflows that perform the Maven version updates upon
the creation of new milestones.
Having one central job simplifies to understand the preparation process.
It also ensures that the steps are always executed in the right order.

The script 'getPreviousRelease.sh' is not considered as it seems to be
unused and is intended to be removed soon.

Author: HannesWell

.github/workflows/README.MD

@@ -6,10 +6,6 @@ This repository contains some workflows that can be shared across all platform r
 
 Check if there is currently a freeze period in place.
 
-## updateRelease.yml
-
-Workflow that can be used to trigger an automatic update to the next release when a new milestone is created
-
 ## checkMergeCommits.yml
 
 Check if a PR contains unwanted merge commits.

.github/workflows/prepareRelease.yml

@@ -59,4 +59,30 @@ Releases are published to <a href="https://repo1.maven.org/maven2/org/eclipse/">
 			scriptPath('JenkinsJobs/Releng/publishToMaven.jenkinsfile')
 		}
 	}
-}
+}
+
+pipelineJob('Releng/prepareNextDevCycle'){
+	displayName('Prepare Next Development Cycle')
+	description('Perform all steps to prepare the next development cycle of Eclipse.')
+	parameters {
+		booleanParam('DRY_RUN', true, 'If enabled, the final publication of all changes is skipped. Useful for debugging and to very that the pipeline behaves as intended.')
+		stringParam('NEXT_RELEASE_VERSION', null, 'Version of the release to prepare, for example: 4.37')
+		stringParam('PREVIOUS_RELEASE_CANDIDATE_ID', null, 'Id of the current release-candiate for the previous release, for example: S-4.36RC2-202505281830')
+		stringParam('M1_DATE', null, 'Milestone 1 end date in the format yyyy-mm-dd, for example: 2025-07-04')
+		stringParam('M2_DATE', null, 'Milestone 2 end date in the format yyyy-mm-dd, for example: 2025-07-25')
+		stringParam('M3_DATE', null, 'Milestone 3 end date in the format yyyy-mm-dd, for example: 2025-08-15')
+		stringParam('RC1_DATE', null, 'Release-Candidate 1 end date in the format yyyy-mm-dd, for example: 2025-08-22')
+		stringParam('RC2_DATE', null, 'Release-Candidate 2 end date in the format yyyy-mm-dd, for example: 2025-08-29')
+		stringParam('GA_DATE', null, 'Final general availability release date in the format yyyy-mm-dd, for example: 2025-09-10')
+	}
+	definition {
+		cpsScm {
+			lightweight(true)
+			scm {
+				github('eclipse-platform/eclipse.platform.releng.aggregator', 'master')
+			}
+			scriptPath('JenkinsJobs/Releng/prepareNextDevCycle.jenkinsfile')
+		}
+	}
+}
+