Prepare MAT 1.17.0 release

[krumts]

It is time to prepare a new release of MAT. The next one would be 1.17.0.
We should also update the MAT release part of the Eclipse simultaneous release. The next one is 2026-06 and I think we are just in time prepare being part of it. Here is the timeline for 2026-06 https://eclipse.dev/simrel/?file=wiki/SimRel/2026-06.md

A few concrete things we need to do:

• In Update Site Management and SimRel Participation #172 it was explicitly requested, that we update the BIRT version we use and contribute to the simrel repo.
• build standalone MAT with a newer Eclipse version, ideally with the to-be-released 2026-06

There are various other todos, and as we haven't practiced releasing for a while, here the links to our dev-docs:

• https://github.com/eclipse-mat/mat/blob/master/dev-doc/Contributor_Reference.md#new-version-development-process
• https://github.com/eclipse-mat/mat/blob/master/dev-doc/Contributor_Reference.md#simultaneous-release-policies

@kgibm @jasonk000 I will take care of updating the various dependencies and preparing the release. I wanted to ask if there are any unfinished / half-finished changes, which you'd like to conclude before the release (2026-06 M3 is on 22 May), or if we are good to release as usual with what what we have.

[krumts]

One further todo - we'd need to require Java 21. The first attempt to use latest BIRT revealed that this requires Java 21 (i.e. we'd need to build with Java 21). Also the platform requires Java 21 meanwhile. Therefore, in order to use a recent platform release for our standalone builds, we'd need increase our requirements to 21.

This was discussed on the mailing list in Jan 2025, and back then we stayed with a lower Java requirement, but I think the time has come to move on.

[krumts]

I was able to make a contribution to 2026-06 M1.
I also created a release record for 1.17.0 (still empty) and set the release data to the one for the simrel.