feat(auth): Add initial support for console session credentials (#8370)

## Problem

AWS Toolkit needs to support console session credentials to enable new
AWS CLI console authentication features which requires
`fromLoginCredentials` from AWS SDK v3.936.0 credential providers.
Currently, profiles with `login_session` credentials are not recognized
as valid credentials.

Learn more:
https://aws.amazon.com/about-aws/whats-new/2025/11/console-credentials-aws-cli-sdk-authentication/


## Solution

* Add CONSOLE_SESSION ('login_session') as a supported credential type
* Implement credential provider using [AWS SDK
fromLoginCredentials](https://www.npmjs.com/package/@aws-sdk/credential-providers#fromLoginCredentials)
* Handle initial authentication flow and state transitions
* Maintain credential caching and validation

This change enables the basic flow of reading and using console session
credentials from shared credentials files. **Credential refresh and
reauthentication flow** will be implemented in a future PR.

<img width="1716" height="1001"
alt="console-session-test-profile-show-in-list-connections-and-explorer"
src="https://github.com/user-attachments/assets/dcbfa671-50de-4b50-b2fb-329873d6b5f0"
/>
---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Author: keenwilson