(SP: 3) Create UserAvatar component aligned with design system

[PavloButynets]

Description:

Implement a reusable UserAvatar component that meets the design system standards. This component will be used throughout the application to maintain consistency in user avatar styles, behavior, and accessibility.

[Figma]

Requirements:

Styles:

Follow design system variables for colors, icons, padding, and other styles.
-Support different variants (check, monogram, avatar, photo).
-Provides a label that signals online status

Props:

-variant: Defines type (check, monogram, avatar, photo).
-size: Supports different sizes (sm, md, lg).
-src: Provide URL for photo (for the type photo)
-monogram: Provide text for the monogram
-isOnline: The label is displayed when true(user is online).
-onClick: A callback function that processes the event of clicking on the icon.

Don't forget to cover component with tests and add to the storybook