Build/Test Tools: Bump bundled Gutenberg build to `0e198c7`

[adamsilverstein]

Core bundles a pre-built copy of Gutenberg, pinned by commit SHA in the custom gutenberg.sha field of package.json. This ticket bumps that pin to 0e198c7ac7ca634e73ded9220ce048c0302174dd and refreshes the regenerated build artifacts.

The pin tracks the wp/next branch rather than Gutenberg trunk: trunk currently requires React 19 while core ships React 18, so a trunk-based bundle breaks the block editor. 0e198c7 is the current tip of wp/next, is React-18 compatible, and carries the HEIC client-side code.

Notes

• The changed files under src/wp-includes/{blocks,assets,build,images} are regenerated Gutenberg build output, produced by npm run gutenberg:download.
• package.json's gutenberg.sha field is the only hand edit; package-lock.json is unaffected, because the SHA lives in a custom field rather than the npm dependency tree.

Patch

• ​PR 12009 - update/bundled-gutenberg-0e198c7

Steps to reproduce / verify

1. Apply the patch (or check out ​PR 12009).
2. Run npm run build and confirm the block editor loads without React initialization errors.

## What

Bumps the bundled Gutenberg build to 0e198c7ac7ca634e73ded9220ce048c0302174dd (current tip of the wp/next branch) and updates the regenerated build artifacts.

This is a one time bump to bring Guternberg up to date in core since the trunk code freeze. In the future we will settle on a regular cadence to update this SHA.

## Why

Needed to bring Gutenberg up to date and enable backports to function correctly.

wp/next is used rather than Gutenberg trunk because trunk currently requires React 19 while core ships React 18; 0e198c7 is React-18 compatible and carries the HEIC client-side code.

## Notes

• The 114 changed files under src/wp-includes/{blocks,assets,build,images} are regenerated Gutenberg build output, produced by npm run gutenberg:download.
• package.json's gutenberg.sha field is the only hand edit; package-lock.json is unaffected (the SHA lives in a custom field, not the npm dependency tree).

I noticed an experiments folder in build/pages and a route folder 'experiments-home' - do those belong in core?

It would be good to land ​https://github.com/WordPress/gutenberg/pull/76715 - short of that, should those folders be excluded from the core commit.

I'm not sure how to review such PRs. I'd appreciate pointers!