IC:2021-03-23, Add FastTracked osal PRs

nasa/osal#890 - Move copyblock size to a #define and add comments
nasa/osal#891 - Removed rogue while loop
nasa/osal#892 - Scripted replacement for #include <os and #include <OSC_ matches of < and > with "
nasa/osal#893 - Consolidates the duplicated switch in OS_SocketOpen_Impl
nasa/osal#894 - Add `const` to input pointers
nasa/osal#895 - Removed network prototypes defined in osapi_sockets.h that are also in osapi_network.h
nasa/osal#896 - Removes NULL redefine from common_types.h
nasa/osal#912 - Add Contributing Guide