Separate gci-core and gci-common, rename "gci-common" to "eip-interface", and rename "EIS_Intf" to "AP-Task"

• gci-core and gci-common are actually independent components that already come with a separate library. However, they both share the identical header files, which should be changed.
   
• Change the name from "gci_common" to "eip_interface", since this component is not related to GCI at all. Having "gci" in the name and especially in function names confuses and makes it hard to read/understand the source code.
  All realted functions need to be renamed accordingly using the new prefix "eip_eif_" (instead of "eip_gci_").
   
• Change the name of the folder "eip" to "eip_core".
   
• Change the name of the folder "EIS_Intf" to "AP_Task"
   
• Change the name of the folder "Eip_RcXBindings " to "eip_rcXBindings "

The EtherNet/IP project shall look like the following at the end:

eip
  |-- AP_Task
  |-- eip_rcXBindings
  |-- eip_core
  |-- eip_gci
  |-- eip_interface
  |-- target_common