SDK Logger does not flush logs to file unless Application is shutdown

[dhaval24]

When using the InternalSdkLogger in "FILE" mode, it is unable to stream the logs to the file. The current implementation only writes to the file (i.e flushes the FileWritter when application is shut down). This behavior should be changed.

Instead users would like to see the logs flowing continuously, therefore it would make sense to flush() after every log statement is written to FileWriter.

This won't be CPU Intensive because by default we have already modified the behavior of the SDK to enable cold start (no logging except critical logAlways messages in case of disaster event).

PS: I would highly recommend moving to SLF4J. The current implementation of FileLogger tries to mimic RollingFileAppender in Log4j / Logback but is pretty nacent. This also doesn't provide users with the flexibility to redirect the logs to the desired single place. Ideally there is always a requirement to pump all the application logs to single location and our InternalLogger is a barrier for this.