Several independent classes were mashed together in mcusupportoptions.cpp
This patch moves McuToolChainPackage together with McuPackage,
McuTarget to its own header+source pair, and
McuKitManager to its own header+source pair.
Task-number: QTCREATORBUG-26890
Change-Id: I0b51da4e1cae5a976201dffd290a665eaa318b33
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>
Introduced Package interface for mocking purposes.
Made some functions visible in headers for testing.
Added basic test skeleton for mcu plugin.
run cmd: `qtcreator -test McuSupport`
Change-Id: I1011d49052bd8c894da393d8a285b241682f1f94
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>
