feat: Add support for strategy="worker" in App Router

[piotrski]

What?

This PR adds support for the 'worker' strategy in the <Script> component when using the App Router with nextScriptWorkers enabled. It also introduces a verification step to ensure that the Partytown component is properly set up in the root layout when using the App Router.

Why?

Previously, using strategy="worker" in the <Script> component worked in the Pages Router but not in the App Router. In the App Router, the <Script> component would fail silently without any warning or error, causing scripts intended to run in a web worker to not execute. Developers might be unaware that they need to include the Partytown component in their root layout for the setup to work correctly, and this requirement was only documented, which could be easily overlooked. This PR addresses these issues to improve developer experience and ensure consistent script handling in both routing systems.

How?

• Script Component Update: Modified the <Script> component to handle the 'worker' strategy in the App Router by rendering a <script> tag with type="text/partytown" and passing the appropriate properties.

• Verification Function Enhancement: Updated verifyPartytownSetup to check if the Partytown component is imported and used in the root layout file when using the App Router. If not, it logs a warning to inform the developer.

• Bundler Setup Adjustment: Modified setup-dev-bundler to pass appDir to verifyPartytownSetup, enabling the new verification step during development.

Fixes #54431

[ijjk]

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