Add private endpoints and update versions to be alligned with SCEPman 2.8

[Utesgui]

• add private endpoints to storage + kv
• add vnet-integration to app(s)
• adjust networking + rules
• block external access
• switch to .net v8.0
• upgrade provider version
• update Readme + advanced example

[bb-froggy]

IP-Ranges

In the current code in the PR, the VNET has 10.255.255.0/24 by default with the two subnets 10.255.255.0/25 and 10.255.255.128/25. The ARM-Template originally used the 10.0.0.0/16 IP range for the VNET. Although there is usually no need to connect the VNET to any other network, Azure checks for collisions even with unconnected VNETs, so it now uses the more random 10.142.0.0/16.

I suggest to have the TF default also use a more random VNET IP range like 10.158.200.0/24 for the VNET.

I further suggest to not assign the whole address space to existing Subnets and leave some IPs for additional subnets possibly needed in the future. Although there are no specific plans for this, it is the case for the ARM deployment and if it is ever needed, we might want to other Subnets in the existing IP range. I suggest we use 3 instead of 1 bit for the prefix, leaving 5 bit for the subnet with 32-2=30 IPs in each subnet by default.

Everything else

Looks good so far, but I will do some testing.