Allow editing of existing network configuration

[dhiltgen]

Since networks are a shared resource, forcing the user to tear them down if they decide some setting needs updating could be disruptive to running production workloads. Some settings on a network could be changed after the network is created without impacting the existing workloads running on that network.

Some ~simple examples:

• Labels
• Enabling manually-attachable

Others to consider:

• Name - might break assumptions elsewhere... but theoretically this should be possible
• Adding allocation ranges
• Changing MTU

[GordonTheTurtle]

@dhiltgen It has been detected that this issue has not received any activity in over 6 months. Can you please let us know if it is still relevant:

• For a bug: do you still experience the issue with the latest version?
• For a feature request: was your request appropriately answered in a later version?

Thank you!
This issue will be automatically closed in 1 week unless it is commented on.
For more information please refer to #1926