Upload Media: follow up for PR feedback

[adamsilverstein]

Description

Follow up to #74355

Follow-up fixes from PR review feedback on the client-side image sub-size generation feature.

1. Rename vips.ts to index.ts instead of adding a separate index.ts re-export file

File: packages/upload-media/src/store/utils/index.ts

The current index.ts just re-exports everything from ./vips. Instead of having a separate index.ts file, we should simply rename vips.ts to index.ts.

2. Use file:../vips reference for @wordpress/vips dependency

File: packages/upload-media/package.json

The @wordpress/vips dependency is currently set to "1.0.0-prerelease", but since it's a package in the same monorepo, it should use a file:../vips reference instead.

- "@wordpress/vips": "1.0.0-prerelease",
+ "@wordpress/vips": "file:../vips",

Parent issue

Part of #74333

[adamsilverstein]

Fixed in #75646