fix(pallet-tfgrid): improve IP validation

[renauter]

Description

1. Improve IP validation according to the following rules:
   • The gateway IP must be in the same subnet as the IP
   • The gateway IP must not be same as the public ip
2. Apply validation while inserting public IP in create_farm() call
3. Create a migration to remove invalid public ips from existing farms in storage

Related Issues:

• Fixes A public ip on the farm public IP list cannot be the same as the gateway #869

Checklist:

Please delete options that are not relevant.

• My change requires storage migration and I have included and tested it following fork off and try_runtime instructions.
• I have added tests to cover my changes.
• My commits follow this conventional commits guide.

[xmonader]

@coesensbert anything else that can help improving the experience regarding this?

[coesensbert]

@coesensbert anything else that can help improving the experience regarding this?

Can not think of anything to add. Last attempt was pretty thorough.