Added Prepend/Extend Trace Methods for Scatter3D plots

[DaltonBritton]

Description

This pull request introduces two new methods, PrependTraces3D and ExtendTraces3D, to enhance the functionality of Scatter3D plots. These methods allow users to efficiently add data points to existing traces at the beginning or end of the trace array, respectively.

Motivation

Currently, Scatter3D plots lack native support for appending or prepending data to existing traces without reconstructing the entire trace array. These new methods address this limitation by providing efficient ways to update trace data, improving the usability and performance of Scatter3D plots.

Changes Made

Added PrependTraces3D method(as well as variations) to insert data points at the beginning of a trace.
Added ExtendTraces3D method(as well as variations) to append data points to the end of a trace.
Updated documentation and created Scatter Chart 3D page