Automatically generate runtime config types from nitro.config the same as Nuxt

[McPizza0]

Describe the feature

In Nuxt runtimeConfig keys/values are typed. This improves DX considerably when accessing vis useRuntimeConfig()

Nitro has not yet implemented this, which can cause some confusion for users coming over from Nuxt

Result: useRuntimeConfig() should be aware of the keys that exist in nitro.config.ts, and provide correct types

Additional information

• [ ] Would you be willing to help implement this feature?