feat(toolkit): Improved welcome component for Assistants (#511)
* refactor: Update getCohereColor usage in multiple components
Refactor the usage of the getCohereColor function in the Welcome, DataSourceMenu, AgentCard, and DiscoverAgentCard components. This change improves code readability and maintainability by calling the function with the appropriate arguments and explicitly specifying the background parameter. It ensures consistent usage of the function across these components.
* refactor: Update getCohereColor usage in multiple components
* refactor: Update getCohereColor usage in multiple components