chore: [app-router-migration 34] migrate the "/auth/logout" and "/auth/signin" pages

[r4zendev]

What does this PR do?

• This PR migrates the /auth/logout and /auth/signin pages to the app directory (which runs under the App Router).
• Using /future/auth/logout is available at all times and is supposed to log the user out as /auth/logout page does.
• However signin page (or fragment) was used before should behave the same using the /future/auth/signin route.

Requirement/Documentation

• If there is a requirement document, please, share it here.
• If there is ab UI/UX design document, please, share it here.

Type of change

• [x] Chore (refactoring code, technical debt, workflow improvements)
• [x] New feature (non-breaking change which adds functionality)

How should this be tested?

• Using /future/auth/logout is available at all times and is supposed to log the user out as /auth/logout page does.
• However signin page (or fragment) was used before should behave the same using the /future/auth/signin route. It was not tested locally.

Mandatory Tasks

• [x] Make sure you have self-reviewed the code. A decent size PR without self-review might be rejected.

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