Enable filter in log4j ApplicationInsightsAppender

[microsoft]

Enable filter in log4j ApplicationInsightsAppender

[dhaval24]

@tobiasdiez thank you very much for the input. I will soon push out a PR. But most likely, it won't be a part of stable release of 2.0.0-BETA, instead would come out in 2.0.1 release as this would be a new feature, and just would defy the transition of Beta to stable.

[dhaval24]

@tobiasdiez could you please shed some more details on this issue? Also, I see you suggesting a fix in the issue discussion. We are very open to contributions and would be really great if you could send a PR if it is possible ?

[tobiasdiez]

Sadly, I don't have time right now to create a PR but, of course, I'm happy to provide more details.

The default log4j2 appender accept the options filter, layout, ignoreExceptions (see AbstractAppender). The ApplicationInsightsAppender should also support these basic settings. For this, the factory method
https://github.com/Microsoft/ApplicationInsights-Java/blob/36214d5c28eb975e008c5b7c60c4840fdd10ec20/logging/log4j2/appenderSrc/main/java/com/microsoft/applicationinsights/log4j/v2/ApplicationInsightsAppender.java#L81-L83
needs to be extended by the arguments @PluginAttribute("ignoreExceptions") boolean ignoreExceptions, @PluginElement("Layout") Layout layout, @PluginElement("Filters") Filter filter (see log4j documentation for an example. What is not shown in the example is that you simply pass these arguments to the parent constructor.).
Moreover, the log4j documentation suggests to use the builder pattern.