Add LogLevelConfigurator

Sources/ElixxirDAppsSDK/LogLevelConfigurator.swift

+import Bindings
+
+public struct LogLevelConfigurator {
+  public var set: (LogLevel) throws -> Void
+
+  public func callAsFunction(logLevel: LogLevel) throws {
+    try set(logLevel)
+  }
+}
+
+extension LogLevelConfigurator {
+  public static func live() -> LogLevelConfigurator {
+    LogLevelConfigurator { logLevel in
+      var error: NSError?
+      let result = BindingsLogLevel(logLevel.rawValue, &error)
+      if let error = error {
+        throw error
+      }
+      if !result {
+        fatalError("BindingsLogLevel returned `false` without providing error")
+      }
+    }
+  }
+}
+
+#if DEBUG
+extension LogLevelConfigurator {
+  public static let failing = LogLevelConfigurator { _ in
+    struct NotImplemented: Error {}
+    throw NotImplemented()
+  }
+}
+#endif