[dev] Deduplicate ingress/egress subnets and addresses for NetworkInfo results

[achilleasa]

Description of change

Due to the way that addresses are being collected and merged together by the machiner and instancepoller workers, we may end up with duplicate entries for the public IP addresses when running on aws substrates (for more information see this related bug).

As a result, network-get may potentially return duplicate entries as shown in https://bugs.launchpad.net/juju/+bug/1864072 which this PR masks by filtering the output of the NetworkInfo API call at the facade level to remove duplicates before returning the result back to the client.

This particular route (deduplication vs fixing the problem at the core) was chosen after considering the fact that there is active ongoing (longer-term) work with networking internals which will eventually fix the problem. The proposed solution ensures that consumers get the right result while still buying us additional time to land a better fix.

QA steps

# Install juju from snap
$ /snap/bin/juju bootstrap aws --credential aws --no-gui
$ /snap/bin/juju deploy percona-cluster
$ /snap/bin/juju run --unit percona-cluster/0 'printenv JUJU_VERSION'
2.7.6

# Notice that network-get returns duplicate entries for bind/ingress addresses
$ /snap/bin/juju run --unit percona-cluster/0 'network-get cluster'
bind-addresses:
- macaddress: 0e:c7:44:73:f3:07
  interfacename: ens3
  addresses:
  - hostname: ""
    address: 172.31.46.122            <--+
    cidr: 172.31.32.0/20                 | Dup
  - hostname: ""                         |
    address: 172.31.46.122            <--+
    cidr: 172.31.32.0/20
- macaddress: ee:19:50:1f:3e:9a
  interfacename: fan-252
  addresses:
  - hostname: ""
    address: 252.46.122.1
    cidr: 252.32.0.0/12
egress-subnets:
- 172.31.46.122/32
ingress-addresses:
- 172.31.46.122                      <--| Dup
- 172.31.46.122                      <--+
- 252.46.122.1

# Upgrade your controller to the version from this PR
$ juju upgrade-controller --build-agent

# Notice that network-get filters duplicates
$ juju run --unit percona-cluster/0 'network-get cluster'
bind-addresses:
- macaddress: 0e:c7:44:73:f3:07
  interfacename: ens3
  addresses:
  - hostname: ""
    address: 172.31.46.122
    cidr: 172.31.32.0/20
- macaddress: ee:19:50:1f:3e:9a
  interfacename: fan-252
  addresses:
  - hostname: ""
    address: 252.46.122.1
    cidr: 252.32.0.0/12
egress-subnets:
- 172.31.46.122/32
ingress-addresses:
- 252.46.122.1
- 172.31.46.122

Bug reference

https://bugs.launchpad.net/juju/+bug/1864072

[manadart]

Code and QA all good here.

[manadart]

Yes.

[achilleasa]

!!build!! (BootstrapSuite timeout)

[achilleasa]

$$merge$$