Custom LoggerFactory for log4cxx

FileLoggerFactory simply outputs logs to a single file.
If users want to rotate log files, they need to implement custom LoggerFactory by themselves.
Log4cxxLogger was deleted in #283, but this is useful for users.

So I would like to recover Log4cxxLogger.
I would not create specialized methods for Log4cxxLogger as there used to be, but would like to make it one of the options in the same category as ConsoleLoggerFactory and FileLoggerFactory.
https://github.com/apache/pulsar-client-cpp/pull/283/files#diff-abb02af9369945477ebc3329b299544ba67e214ac3f36c55b1f9e27f68469abf
If we want to avoid embedding it as a build option, we can separate the client and logger packages.

首先查看 #283 的 diff 以及当前的 ConsoleLoggerFactory 和 FileLoggerFactory 实现，以了解 logger 选项是如何公开的。在决定采用内置 build 选项还是拆分为独立的 client/logger package 之前，先检查 build 和 package 布局。完成的标准是将 Log4cxxLogger 恢复为同级选项，并且用户无需专用方法即可使用它进行自定义 log rotation。

由索引模型根据 Issue 内容生成。