Update to Theia IDE 1.55.x

[sdirix]

Update and release aligned with Theia 1.55.x

Required Steps

• Merge latest Theia Blueprint community release commit
• if required: Update Theia to latest version of said community release
• Update all consumed Theia extensions and VSCode extensions
• Test packaged Electron Blueprint locally
• Test Browser variant locally
• Test Docker variant locally
• Run E2E tests locally (https://github.com/eclipse-cdt-cloud/cdt-cloud-blueprint?tab=readme-ov-file#running-e2e-tests)

After Merge

• Verify that Jenkins pipeline completed successfully
• Download a previous release and check that update to latest version completes successfully

Deploy to try.theia-cloud.io:

• Push docker image with version tag to registry via GH action
• Update deployment file to use newly pushed docker image
• Apply the deployment file to the cluster
• Verify that updated CDT Cloud Blueprint Try Online is available and works

Release announcement:

• Announce release on the cdt-cloud-dev mailing list