Add ValueProvider.kt

dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/values/ValueProvider.kt

@@ -9,9 +9,15 @@ public fun interface ValueProvider {
     public fun getValue(name: Name): Value?
 }
 
+public fun ValueProvider.getValue(key: String): Value? = getValue(Name.parse(key))
+
 /**
  * An object that could consume values
  */
 public interface MutableValueProvider : ValueProvider {
     public fun setValue(name: Name, value: Value?)
 }
+
+public fun MutableValueProvider.setValue(key: String, value: Value?) {
+    setValue(Name.parse(key), value)
+}