feat(chat): Implement federated logout with custom session termination flow

[valerydluski]

Description:

Implemented federated logout functionality, allowing users to sign out both locally and from the external identity provider (IDP). The custom logout flow handles session termination and redirects to the federated logout endpoint when available.

Issues:

UI changes

No UI changes involved.

Checklist:

• the pull request name complies with Conventional Commits
• the pull request name starts with fix(<scope>):, feat(<scope>):, feature(<scope>):, chore(<scope>):, hotfix(<scope>): or e2e(<scope>):. If contains breaking changes then the pull request name must start with fix(<scope>)!:, feat(<scope>)!:, feature(<scope>)!:, chore(<scope>)!:, hotfix(<scope>)!: or e2e(<scope>)!: where <scope> is name of affected project: chat, chat-e2e, overlay, shared, sandbox-overlay, etc.
• the pull request name ends with (Issue #12345) (comma-separated list of issues)
• I confirm that I do not share any confidential information like API keys or any other secrets and private URLs

[akryvasheyeu]

/deploy-review

Environment URL: https://chat-ai-dial-chat-pr-2079.nightly-test.deltixhub.io
E2E tests status: failed

[IlyaBondar]

/deploy-review

Environment URL: https://chat-ai-dial-chat-pr-2079.nightly-test.deltixhub.io
E2E tests status: failed

[IlyaBondar]

/deploy-review

Environment URL: https://chat-ai-dial-chat-pr-2079.nightly-test.deltixhub.io
E2E tests status: success