T7218 Improve Contribution Checklist (to include code, component and design evaluation guidelines

The current contribution checklist is focused on the development of APIs and Apertis specific codebases. This is not something that we are actively doing much anymore and doesn't provide any guidance on accepting changes to existing components, addition of components or submission of concept designs.

Change the contribution checklist to focus on these topics that we are actively participating in. Split out the development process as this is much more of a practical guide than a policy.