Add support for exporting contacts to ScenEdit_ExportScenarioToXML

[duyminh1998]

Why

As a

user of pyCMO

I want

to be able to export a side's contacts from the Steam version of Command

So that

I can use contacts information to target enemy units

Acceptance Criteria

Given

ScenEdit_ExportScenarioToXML currently does not support a side's contacts

When

we add the ability to export contacts to the ExportSidesToXML function

Then

we can export contacts from the game and use it for our RL agents