Create Sidebar and SidebarItem components

[KonradSzwarc]

Acceptance criteria:

• All states of SidebarItem and Sidebar match mockups.
• Sidebar item can receive children, count (optional).
• Can receive icon and iconSelected props (both or none).
• Avatar in the bottom of the Sidebar uses a re-exported Avatar component from Chakra UI.
• There are playground and states stories for the SidebarItem component.
• There is a story for the Sidebar component.

Mockups:
SidebarItem
Sidebar

[github-actions]

Branch issue-10-Create_Sidebar_and_SidebarItem_components created!