Add new json provider to log root stack trace elements

[worldtiki]

Hi 👋

I'm opening a draft for a new json provider.
It complements existing ones (ThrowableRootCauseClassNameJsonProvider, StackTraceJsonProvider, ...).
This provides details about the context of the exception, ie, it doesn't tell us that a NullPointerException occurred but rather that it occurred in MyClass.myMethod().

For example, MyClass.doSomething() calling MyOtherClass.doSomethingRisky() which throws an error will produce the following output.

{
   "root_stack_trace_element":{
      "class_name":"com.example.stacktraces.MyOtherClass",
      "method_name":"doSomethingRisky"
   }
}

[nikos912000]

Hi there. Is there any update on this?
This feature is pretty useful.

[philsttr]

This looks great! Thank you for submitting the PR. I had one minor suggestion. After that is resolved I'll get it merged.