Add support for the NetTrace EventPipe file format

Add support for the NetTrace EventPipe file format

Right now the new format is not on by default, but it can be enabled using COMPlus_EventPipeNetTraceFormat = 1 for testing purposes. The plan to have a follow up PR that will add shipping configuration mechanisms and change the default setting.

See the documentation in the PerfView repo for more details about the format. At a glance the goal is to create a format that is more efficient to produce, has a smaller on disk size, and offers enhanced functionality in a few areas:
a) 64 bit thread id support
b) Detection of dropped events via sequence numbers
c) Better support for extracting subsets of the file

Together with the change there was also some refactoring of the EventPipeBufferManager and EventPipeThread.

This change addresses (at least in part) the following issues:
#19688, #23414, #24188, #20751, #20555, #21827, #24852, #25046