This is the sub-task for the group impersonation work. https://issues.redhat.com/browse/CONSOLE-4734 

This sub-task involves creating the frontend for the user impersonation modal. The modal will serve as the primary interface for initiating an impersonation session. The design and layout should be based on the provided Figma prototype.

Acceptance Criteria:

• The modal can be triggered in two ways, based on the figma:

1. 1. From the top-right corner dropdown menu: The "Username" input field is editable.

1. 1. From the user management section (for a specific user): The "Username" input field is pre-populated with the selected user's name and is set to readonly.

• The modal includes "Impersonate" and "Cancel" buttons.

• No autocomplete functionality is required for the "Username" field in this iteration

Technical Notes:

• The "Username" input field component should have a readonly property that can be toggled based on how the modal is triggered, and there should be a way to pass the username information.

• This sub-task is focused solely on the frontend implementation of the modal. The logic for handling the impersonation itself will be addressed in separate tasks.