Fix some issues and enable ARM architecture build

[XzuluX]

This merge request provides fixes for the following issues:

• Fix serial RX communication issue and improve buffer handling, tested with Beckhoff EL6021
• Fix multiple crashes occurring within the EcHL.PO2SOCallback
• Add IgnoreSMConfig property to optionally bypass the Sync Manager configuration for some slaves (The Bechhoff EL6601 does not support any cyclic SyncManager channels and uses only SM0/SM1 for mailbox data. Its SyncManager configuration is fixed and cannot be modified via SDO writes)

Additionally, init_solution.ps1 and SOEM.PInvoke.csproj have been updated to enable native builds on ARM architectures.