Prepare for Storybook 10: Output ESM-only

[JReinhold]

Updated addon-kit to only output ESM, in accordance with Storybook 10.

• Removed the exportEntries bundle option, as it was ambiguous and unnecessary. It should be very rare that addons will have code that should both be importable by end-users in Node and manager/preview. So now all entry points must either be node, manager or preview types.
• Upgraded all dependencies

Do not merge until Storybook 10 is released

Before merging:

• Update docs/addons/addon-migration-guide.mdx to point to main instead of this branch

- Storybook 10 requires all addons to be built as ESM-only. This change simplifies the build process and reduces maintenance overhead. You'll need to make many changes to `tsup.config.ts`, so it can be easier to copy the reference file in the [`addon-kit` repository](https://github.com/storybookjs/addon-kit/blob/esm-only/tsup.config.ts).
+ Storybook 10 requires all addons to be built as ESM-only. This change simplifies the build process and reduces maintenance overhead. You'll need to make many changes to `tsup.config.ts`, so it can be easier to copy the reference file in the [`addon-kit` repository](https://github.com/storybookjs/addon-kit/blob/main/tsup.config.ts).

[Sidnioulz]

@JReinhold FYI the addon migration guide currently refers to this branch's tsup config file as addon authors start migrating ahead of release.

But once this is merged, I'll need to know so I can go and point that URL to main on the addon-migration-guide instead of esm-only.