Build: Wrap script bundles in an IIFE to contain 'use strict'

[westonruter]

This updates core to use Gutenberg with the changes in WordPress/gutenberg#79792 for testing.

Trac ticket: https://core.trac.wordpress.org/ticket/65515

Use of AI Tools

None for this PR, but see the Gutenberg PR for its AI disclosure.

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

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[github-actions]

Test using WordPress Playground

The changes in this pull request can previewed and tested using a WordPress Playground instance.

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Test this pull request with WordPress Playground.

[westonruter]

@desrosj FYI: I updated gutenberg.sha to point to a PR and it causes unit test failures unexpectedly.