Jw/merge initial context

[jeremy-clerk]

Description

If the router is created with an initial context, the clerkInitialState overwrites the context and it is lost in the tree. This patch will merge the original/existing context with the clerkInitialState.

Checklist

• [x] npm test runs as expected.
• [x] npm run build runs as expected.
• [ ] (If applicable) JSDoc comments have been added or updated for any package exports
• [ ] (If applicable) Documentation has been updated

Type of change

• [x] 🐛 Bug fix
• [ ] 🌟 New feature
• [ ] 🔨 Breaking change
• [ ] 📖 Refactoring / dependency upgrade / documentation
• [ ] other: