[Notebook Migration] Add notebook-migration-service for Texera and Jupyter communication and Database communication

[zyratlo]

Task Summary

Introduce the microservice that mediates between Texera and the JupyterLab docker stack (landed in migration-tool-jupyter-docker).

Scope

Adds a new SBT subproject notebook-migration-service plus shared config and a frontend proxy route:

• notebook-migration-service/build.sbt, project/build.properties — module SBT setup.
• src/main/scala/.../NotebookMigrationService.scala — Dropwizard Application entry; serves at /api/* on port 9098, registers the resource, initializes the shared DB connection from StorageConfig.
• src/main/scala/.../NotebookMigrationServiceConfiguration.scala — Dropwizard Configuration subclass.
• src/main/scala/.../resource/NotebookMigrationResource.scala — five REST endpoints under /notebook-migration:
  • GET /get-jupyter-url
  • GET /get-jupyter-iframe-url
  • POST /set-notebook (pushes a notebook into JupyterLab via its /api/contents API)
  • POST /store-notebook-and-mapping (persists notebook + workflow-notebook mapping to Postgres)
  • POST /fetch-notebook-and-mapping (retrieves the latest pair for a workflow/version).
• src/main/resources/logback.xml, notebook-migration-service-web-config.yaml — logging and Dropwizard server config.
• Root build.sbt — registers the subproject in the TexeraProject aggregation
• common/config/src/main/resources/storage.conf + StorageConfig.scala — new jupyter { url = "http://localhost:9100" } block with STORAGE_JUPYTER_URL override, accessed by the resource as StorageConfig.jupyterURL.
• frontend/proxy.config.json — routes /api/notebook-migration/* to http://localhost:9098 for dev.

Task Type

• Refactor / Cleanup
• DevOps / Deployment / CI
• Testing / QA
• Documentation
• Performance
• Other

[zyratlo]

/parent-issue #4301