feat(ui): Add drag-and-drop support for importing integration XMLs as flow diagrams

[a-asaad]

Motivation and Context

In addition to current support for dropping exported Flow JSON files, the Canvas can now accept dropped integration XML files. This makes it easier to keep Flow diagrams in-sync with executable XML logic, enabling faster iteration and up-to-date documentation for routes.

Details

The critical logic is contained in the eipFlowToDiagram.ts, which converts the EipFlow response to a format compatible with the app's store. Note, this feature depends on #29, so the flow-translator service must be available for the XML file import to function.

High-level steps:

• Drop a valid integration XML file
• The file's content is sent to the flow-translator service's toFlow endpoint
• The EipFlow response is transformed and imported into the app's state store
• The Canvas displays the updated diagram

Checklist

• The PR follows the branch and commit styles outlined in the CONTRIBUTING doc
• (UI changes only) Linting and formatting checks pass locally with the new changes (npm run precommit from the ui directory)