FIREFLY-1927: Refactor ObsCorePackager code

[kpuriIpac]

Ticket: FIREFLY-1927

• ObsCorePackager was becoming too big.
• Logically split file up into smaller chunks of code (following separation of concern as much as possible) that should be much easier to maintain moving forward.
• Open to feedback on further improvments!

Testing:

• Test downloads in the following apps (one download per app to verify the download script is working as before is sufficient)
• Firefly: https://fireflydev.ipac.caltech.edu/firefly-1927-obscore-refactor/firefly
• Euclid: https://firefly-1927-obscore-refactor.irsakubedev.ipac.caltech.edu/applications/euclid
• Spherex: https://firefly-1927-obscore-refactor.irsakubedev.ipac.caltech.edu/applications/spherex
• DCE: https://firefly-1927-obscore-refactor.irsakubedev.ipac.caltech.edu/irsaviewer/dce

[Copilot]

Pull request overview

This PR refactors the ObsCorePackager class by splitting it into smaller, more maintainable modules following separation of concerns. The large monolithic class (~630 lines) has been reorganized into a main class and several utility classes.

• Main class moved from server.query to server.packagedata.obscorepackager package
• Functionality split into utility modules: DatalinkParser, ServiceDescriptorUtil, ObsCoreUrlUtil, ObsCorePositionUtil, and ObsCoreFilenameUtil
• Created empty test class stub

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
src/firefly/java/edu/caltech/ipac/firefly/server/query/ObsCorePackager.java	Deleted original 630-line class
src/firefly/java/edu/caltech/ipac/firefly/server/packagedata/obscorepackager/ObsCorePackager.java	New main class with core orchestration logic and constants
src/firefly/java/edu/caltech/ipac/firefly/server/packagedata/obscorepackager/datalink/DatalinkParser.java	Extracted datalink parsing logic
src/firefly/java/edu/caltech/ipac/firefly/server/packagedata/obscorepackager/datalink/ServiceDescriptorUtil.java	Extracted service descriptor URL construction logic
src/firefly/java/edu/caltech/ipac/firefly/server/packagedata/obscorepackager/util/ObsCoreUrlUtil.java	Extracted URL/extension utility methods
src/firefly/java/edu/caltech/ipac/firefly/server/packagedata/obscorepackager/util/ObsCorePositionUtil.java	Extracted position/coordinate handling logic
src/firefly/java/edu/caltech/ipac/firefly/server/packagedata/obscorepackager/util/ObsCoreFilenameUtil.java	Extracted filename generation utilities
src/firefly/test/edu/caltech/ipac/firefly/server/packager/ObsCorePackagerTest.java	Added empty test class stub

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[loitly]

I reviewed the changes with the developer and suggested a few minor name changes. Other than that, everything looks good.