Update jdtls version from 1.42.0-561 to 1.53.0-873

[stewardc]

Summary

This PR updates the bundled Eclipse JDTLS runtime assets and fixes a reinstallation issue when Serena extracts over an existing read-only file.

What changed

• bumped the default vscode_java_version from 1.42.0-561 to 1.53.0-873
• updated the pinned SHA256 values for each platform-specific vscode-java bundle
• updated bundled JRE paths to 21.0.10
• updated the Eclipse Equinox launcher reference to 1.7.100.v20251111-0406
• centralized the default runtime dependency versions into shared constants to avoid repeating version strings across platforms
• kept version overrides configurable via settings, and added support for overriding the launcher version separately
• made ZIP extraction set an existing target file writable before overwriting it, which avoids failures when re-extracting over a previous read-only install

Why

The JDTLS runtime references were still pinned to an older vscode-java release. The old version fails when a project contains many layers of mutually recursive generics (run Serena against https://github.com/stewardc/mutuallyRecursiveGenericsDemo to see the error). Updating the version resolves this issue.

The extraction fix addresses a practical upgrade path issue: if Serena reuses an existing install directory and encounters a read-only file, extraction can fail instead of refreshing the bundle.

Testing

• added a unit test covering ZIP extraction over an existing read-only file

[stewardc]

New PR with the SHA checks in place.

One thing to note, the workspace config.ini seems to pin the old JDTLS version. I can try to force an update, or leave it as-is (maybe add something to the project readme?) Let me know how you'd like to handle this.

Thanks!

[MischaPanch]

Thanks! I think we need to address the follow-up issue (#1232) first, we shouldn't just overwrite the existing version all the time

[stewardc]

Thanks! I think we need to address the follow-up issue before #1232, we shouldn't just overwrite the existing version all the time

Makes sense - I agree, it felt wrong to just blindly overwrite. If it's not urgent, I can take a look at that issue when I've got some spare time over the next couple of weeks.

[MischaPanch]

It's not urgent, but @opcode81 and I need to converge on the most suitable approach before the issue is addressed. Feel free to comment in the issue to participate in the discussion but I'd ask to refer from making a PR until the solution is sufficiently sketched out in the issue