Support for deep object merging

[JakeStanger]

Currently object merging only takes the immediate children into account.

There may be utility in changing this, or adding additional syntax, to perform a 'deep merge', running the merge against every child object.

Issue originates from the below discussion, which compares the feature to Nix's 'attrset merge':

Discussed in https://github.com/orgs/corn-config/discussions/29

^{Originally posted by **fbewivpjsbsby** November 6, 2023} 1. What version of corn are you using? corn-cli 0.9.2 2. What is your operating system? Windows 10 ### Description It is like nixos module, config will merge when you imports config, [use ```//``` operators](https://ryantm.github.io/nixpkgs/functions/library/attrsets/#function-library-lib.attrsets.mergeAttrsList) or [use mkMerge](https://nixos.org/manual/nixos/stable/#sec-option-definitions-merging). Corn is override attrsets now. ### Steps to reproduce 1. Write this in corn file: ```corn let { $preferences_user_enable = { Value = true Status = "user" } // telemetry $policies_disable_telemetry = { DisableTelemetry = true DisableFirefoxStudies = true } // #TODO 'raw data' need git version corn // theme $policies_theme = { Preferences = { 'toolkit.legacyUserProfileCustomizations.stylesheets' = $preferences_user_enable 'layout.css.backdrop-filter.enabled' = $preferences_user_enable 'widget.non-native-theme.use-theme-accent' = $preferences_user_enable } } $policies_ech = { // ech need enable DNS over HTTPS DNSOverHTTPS = { Enabled = true ProviderURL = "https://1.1.1.1/dns-query" Locked = false ExcludedDomains = [""] } Preferences = { 'network.dns.echconfig.enabled' = $preferences_user_enable 'network.dns.http3_echconfig.enabled' = $preferences_user_enable } } } in { policies = { // telemetry ..$policies_disable_telemetry // ech ..$policies_ech // theme ..$policies_theme } } ``` 2. run ```corn [your corn file name].corn -t json``` It is override by $policies_theme: ```json { "policies": { "DisableTelemetry": true, "DisableFirefoxStudies": true, "DNSOverHTTPS": { "Enabled": true, "ProviderURL": "https://1.1.1.1/dns-query", "Locked": false, "ExcludedDomains": [ "" ] }, "Preferences": { "toolkit.legacyUserProfileCustomizations.stylesheets": { "Value": true, "Status": "user" }, "layout.css.backdrop-filter.enabled": { "Value": true, "Status": "user" }, "widget.non-native-theme.use-theme-accent": { "Value": true, "Status": "user" } } } } ```