Add user based authentication

## Description

The AWS Graph Explorer UI does not support any user authentication/authorisation.

This is a security issue with our use case because the data is very sensitive. Anyone with access to the service URL can access the graph DB data (even though our Neptune DB instances are locked down, the UI is not).

## Preferred Solution

AWS Graph Explorer should have a login page to authenticate users before being allowed access to the UI.

The auth options should be configurable and be optional for open access.

Preferred auth methods (in order of priority):

1. Active Directory (important for our use case)
2. HTTP Basic Authentication
3. Generic LDAP

---

> [!IMPORTANT]
> If you are interested in working on this issue or have submitted
> a pull request, please leave a comment.

> [!TIP]
> Please use a 👍 reaction to provide a +1/vote.
>
> This helps the community and maintainers prioritize this request.