When removing a collaborator, remove their credentials from the project

[christad92]

Today, we don't remove a user's credentials from a project (that uses the credentials) if we are removing the user as a project collaborator. This potential threatens the security of the project and can lead to failed runs if the credential details/permissions change in the future.

When a user is removed as a collaborator in a project, we should remove credentials owned by them. This will ensure that we keep the project secured and that a future change to the credential does not impact the project.

When removing a collaborator, the confirmation message reads "Are you sure you want to remove "rita zagoni" from this project? They will no longer have access. Do you wish to proceed with this action?" but we should extend it to say:

Are you sure you want to remove "user.name" from this project?

They will no longer have access and their owned credentials [list of credentials] will be removed from this project.

Do you wish to proceed with this action?