feat: aggregate defaults and values

- Output merged defaults and values
- Add "check" command

internal/command/testdata/check/defaults.json

@@ -0,0 +1,5 @@
+{
+    "foo": {
+        "bar": "test"
+    }
+}

internal/command/testdata/check/schema.json

@@ -0,0 +1,17 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema",
+    "type": "object",
+    "properties": {
+        "foo": {
+            "type": "object", 
+            "properties": {
+                "bar": {
+                    "type": "string"
+                }
+            },
+            "required": ["bar"]
+        }
+    },
+    "required": ["foo"],
+    "additionalProperties": true
+}

internal/command/testdata/check/values-nok.json

@@ -0,0 +1,5 @@
+{
+    "foo": {
+        "bar": false
+    }
+}

internal/command/testdata/check/values-ok.json

@@ -0,0 +1,3 @@
+{
+    "test": 1
+}