T6121: Extend service config-sync to new sections

Extend service config-sync with new sections:

• LeafNodes: pki, policy, vpn, vrf (syncs the whole sections)
• Nodes: interfaces, protocols, service (syncs subsections)

In this cae the Node allows to uses the next level section
i.e subsection

For example any of the subsection of the node interfaces:

• set service config-sync section interfaces pseudo-ethernet
• set service config-sync section interfaces virtual-ethernet

Example of the config:

set service config-sync mode 'load'
set service config-sync secondary address '192.0.2.1'
set service config-sync secondary key 'xxx'
set service config-sync section firewall
set service config-sync section interfaces pseudo-ethernet
set service config-sync section interfaces virtual-ethernet
set service config-sync section nat
set service config-sync section nat66
set service config-sync section protocols static
set service config-sync section pki
set service config-sync section vrf

(cherry picked from commit 25b611f504521181f85cb4460bfdfd702c377b5e)