Means of only saving set settings

[mgabeler-lee-6rs]

Preflight Checklist

• I have searched the issue tracker for an issue that matches the one I want to file, without success.

Problem Description

Currently WriteConfig() and its variants save all settings, including making any default values explicit.

Proposed Solution

• Expose a ChangedSettings() method similar to AllSettings(), but which only returns values that pass IsSet()
• Expose variations on WriteSettings() that use ChangedSettings() in place of AllSettings()

Alternatives Considered

Re-implementing the core of viper's WriteSettings by hand is possible, but it requires either losing some features or re-implementing many by hand, since the config encoding structures are not exported, nor is the deep key mapping (deepSearch()) used for nested settings.

Additional Information

No response

[github-actions]

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