feat: allow oveeridng nested runtime config with env

[becem-gharbi]

🔗 Linked issue

fix #1830

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Original behaviour
Runtime config properties with object type cannot be replaced by matching env variables.

    runtimeConfig: {
        feature: { // Setting NITRO_FEATURE=false do not work
            options: {  // Setting NITRO_FEATURE_OPTIONS=false do not work
                optionA: true,
                optionB: true
            }
        }
    }

Updated behaviour
Runtime config with object properties can be replaced by matching env variables.

    runtimeConfig: {
        feature: { // Setting NITRO_FEATURE=false works
            options: {  // Setting NITRO_FEATURE_OPTIONS=false works
                optionA: true,
                optionB: true
            }
        }
    }

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[BobbieGoede]

This would be pretty useful, is there anything blocking this from being merged?

[BobbieGoede]

Rebase/merge with main should make the tests pass again, this PR will enable more Nuxt modules to add support for more complex runtime configuration (have a PR lined up for @nuxtjs/i18n built using this code).

Don't mean to rush anyone to merge this, but if I can be of any help to move it along let me know!

[pi0]

Thanks for PR ❤️ and sorry for late review since i needed to properly verify changes.