Fix the customer account implementation to clear all session data on logout

[blittle]

WHY are these changes introduced?

The logout method on the customer account API abstraction does not clear all session data. It only clears customer account api related data. This means if the user attaches any custom data to the session, it will bleed across customer account logins.

WHAT is this pull request doing?

This fixes the logout method to destroy the whole session, preventing any data from bleeding. If for some reason users want to keep custom data in the session, they can pass keepSession: true to the logout method:

export async function action({context}: ActionFunctionArgs) {
  return context.customerAccount.logout({
    keepSession: true
  });
}

HOW to test your changes?

1. Add something to the session inside the customer account pages. For example, on the account.profile.tsx page, add context.session.set('test', 'test ' + new Date().toISOString()); to the action.
2. Log into the app locally
3. Update the profile, so that the action is called and a field is put into the session
4. Logout
5. Make sure the session is cleared
6. Try again with keepSession:true, and make sure the session is persisted.

Post-merge steps

Checklist

• I've read the Contributing Guidelines
• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've added a changeset if this PR contains user-facing or noteworthy changes
• I've added tests to cover my changes
• I've added or updated the documentation

[shopify]

Oxygen deployed a preview of your bl-customer-account-destroy-session branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
metaobjects	✅ Successful (Logs)	Preview deployment	Inspect deployment	April 8, 2025 9:01 PM
custom-cart-method	✅ Successful (Logs)	Preview deployment	Inspect deployment	April 8, 2025 9:01 PM
Skeleton (skeleton.hydrogen.shop)	✅ Successful (Logs)	Preview deployment	Inspect deployment	April 8, 2025 9:01 PM
third-party-queries-caching	✅ Successful (Logs)	Preview deployment	Inspect deployment	April 8, 2025 9:01 PM
classic-remix	✅ Successful (Logs)	Preview deployment	Inspect deployment	April 8, 2025 9:01 PM

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[juanpprieto]

Nice work