Introduce .Net ERP Interface

[PatrickGrub]

Introduce a .Net ERP Interface which exposes the functions what we need from the ERP Team, defined in #97

• [x] Upload interface to Github and Link it to #97
• [x] Implement interface in the dummy plugin
  • [x] ItemService - use it in the service
  • [x] BomService- use it in the service
  • [x] DocumentService- use it in the service
• [x] Wiki for ERP for a quick getting started
• [ ] Teams Wiki for internal: how to integrate the ERP implementation when DLL was delivered

This should be sent to the ERP team in order to give them a precise definition of our needs.

[PatrickGrub]

Added interface to branch https://github.com/coolOrangeLabs/powerGateTemplate/tree/issue-126 , but not finished, only 1 version.

[PatrickGrub]

Related commits after https://github.com/coolOrangeLabs/powerGateTemplate/commit/f48071c8b8ff5cc03884f04cf58c8f5a28973dbc

[PatrickGrub]

• Extended issue: https://github.com/coolOrangeLabs/powerGateTemplate/issues/97
• Created wiki: https://github.com/coolOrangeLabs/powerGateTemplate/wiki/ERP-C%23-API