Fix initializers not being public

Author: Mordil

Sources/NIORedis/ChannelHandlers/RESPDecoder.swift

@@ -37,6 +37,8 @@ public final class RESPDecoder {
         case parsed(RESPValue)
     }
 
+    public init() { }
+
     /// Attempts to parse the `ByteBuffer`, starting at the specified position, following the RESP specification.
     ///
     /// See https://redis.io/topics/protocol

Sources/NIORedis/ChannelHandlers/RESPEncoder.swift

@@ -5,6 +5,8 @@ import NIO
 ///
 /// See: https://redis.io/topics/protocol
 public final class RESPEncoder {
+    public init() { }
+    
     /// Encodes the `RedisValue` to bytes, following the RESP specification.
     ///
     /// See https://redis.io/topics/protocol

Sources/NIORedis/ChannelHandlers/RedisCommandHandler.swift

@@ -7,6 +7,11 @@ public struct RedisCommandContext {
     public let command: RESPValue
     /// A promise expected to be fulfilled with the `RESPValue` response to the command from Redis.
     public let promise: EventLoopPromise<RESPValue>
+
+    public init(command: RESPValue, promise: EventLoopPromise<RESPValue>) {
+        self.command = command
+        self.promise = promise
+    }
 }
 
 /// A `ChannelDuplexHandler` that works with `RedisCommandContext`s to send commands and forward responses.