Create panel component

[Michał Paczyński]

In this task we should create reusable panel component that we will use for realm UI

• panel component should be available in right and left versions
• it should be scrollable in a similar manner as current realm modal - it should have constant top margin and minimum bottom margin to ensure nice empty space even on smaller screens
• scrolling can be handled separately on the left and right versions
• we should be able to add subsections (stake/unstake)
• panel should expand with content

[Jagoda Rybacka]

Resolved by #774