### Motivation and Context
<!-- Thank you for your contribution to the semantic-kernel repo!
Please help reviewers and future users, providing the following
information:
  1. Why is this change required?
  2. What problem does it solve?
  3. What scenario does it contribute to?
  4. If it fixes an open issue, please link to the issue here.
-->
PR that resets app state on log out and fixes some css bugs.

### Description
<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->
- Introduced root reducer that combines all state reducers and defines a
special resetApp reducer that'll handle resetting the entire state
- Added Loading state (before App would show the Login screen again
because there's a split second where the app is unauthenticated before
it's redirected to MSAL logout screen)
- Fixed chatlist timestamp UI error
- Fixed Plugin overflow window

![image](https://github.com/microsoft/semantic-kernel/assets/125500434/0ac48e2b-3fdf-4268-962e-bb438dd97694)


### Contribution Checklist
<!-- Before submitting this PR, please make sure: -->
- [X] The code builds clean without any errors or warnings
- [X] The PR follows SK Contribution Guidelines
(https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
- [ ] The code follows the .NET coding conventions
(https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions)
verified with `dotnet format`
- [ ] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

### Motivation and Context
<!-- Thank you for your contribution to the semantic-kernel repo!
Please help reviewers and future users, providing the following
information:
  1. Why is this change required?
  2. What problem does it solve?
  3. What scenario does it contribute to?
  4. If it fixes an open issue, please link to the issue here.
-->
PR that resets app state on log out and fixes some css bugs.

### Description
<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->
- Introduced root reducer that combines all state reducers and defines a
special resetApp reducer that'll handle resetting the entire state
- Added Loading state (before App would show the Login screen again
because there's a split second where the app is unauthenticated before
it's redirected to MSAL logout screen)
- Fixed chatlist timestamp UI error
- Fixed Plugin overflow window

![image](https://github.com/microsoft/semantic-kernel/assets/125500434/0ac48e2b-3fdf-4268-962e-bb438dd97694)


### Contribution Checklist
<!-- Before submitting this PR, please make sure: -->
- [X] The code builds clean without any errors or warnings
- [X] The PR follows SK Contribution Guidelines
(https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
- [ ] The code follows the .NET coding conventions
(https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions)
verified with `dotnet format`
- [ ] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄