Extend [[ https://github.com/vyos/vyos-1x/blob/c497848082efd62ae8893929afd2530677ce336d/src/services/vyos-http-api-server#L104C7-L121 | ConfigureModel ]] and related modules to support load configuration in JSON format.
```
"configFormat": "json | json_ast | raw (default)
```
Ability to use `load` for some `Section`
For example, for NAT section we want to load via the API
```
{"source": {"rule": {"100": {"outbound-interface": "eth0", "translation": {"address": "masquerade"}}}}}
```
Expected configuration:
```
set nat source rule 100 outbound-interface 'eth0'
set nat source rule 100 translation address 'masquerade'
```