Added imagePlaceholder, imageError and EventListener to Gallery. Compute Input and MessageInput multiline height on mount. Added position prop to Menu. Increased test coverage.
Added imagePlaceholder, imageError and EventListener to Gallery. Compute Input and MessageInput multiline height on mount. Added position prop to Menu. Increased test coverage.

anchorchat/anchor-ui,anchorchat/anchor-ui,anchorchat/anchor-ui