Description field for projects and components

### Describe the problem

There is no place to store some textual information about a project and/or a component.

### Solution brainstorm

Add a "description" field to both the component and project.
It ideally supports markdown the same way as the translation instructions field.
Show it in the Summary box on the Overview tab.

### Describe alternatives you have considered

Using the translation instruction, but these are visible all the time on every screen and only available for projects, not for components.

### Screenshots

_No response_

### Additional context

_No response_