…and model migrate for juju3;

This reverts commit 2311693.

juju#14410

This PR checks if LXD version >= 5.2(if the model's cloud is LXD) when we upgrade a controller/model to 3.0.0+ or migrate a model to a 3.0.0+ controller.

## Checklist

- [x] Code style: imports ordered, good names, simple structure, etc
- [ ] ~Comments saying why design decisions were made~
- [x] Go unit tests, with comments saying what you're testing
- [ ] ~[Integration tests](https://github.com/juju/juju/tree/develop/tests), with comments saying what you're testing~
- [ ] ~[doc.go](https://discourse.charmhub.io/t/readme-in-packages/451) added or updated in changed packages~

## QA steps

```console
# upgrade

$ lxd --version
5.0.0

$ juju models -c k1 --format json | jq '.models[] | {name,"agent-version"}'
{
 "name": "admin/controller",
 "agent-version": "2.9.33.1"
}
{
 "name": "admin/default",
 "agent-version": "2.9.33.1"
}

$ juju version --all
version: 3.0.0-ubuntu-amd64
git-commit: d159efa
git-tree-state: dirty
compiler: gc

$ juju upgrade-controller --build-agent
no prepackaged agent binaries available, using local agent binary 3.0.0.2 (built from source)
ERROR cannot upgrade to "3.0.0.2" due to issues with these models:
"admin/controller":
- LXD version has to be "5.2.0" at least, but current version is "5.0.0"
"admin/default":
- LXD version has to be "5.2.0" at least, but current version is "5.0.0"

# migrate

$ juju add-model m1 -c k1
Added 'm1' model on localhost/localhost with credential 'localhost' for user 'admin'

$ juju models -c k1 --format json | jq '.models[] | {name,"agent-version"}'
{
 "name": "admin/controller",
 "agent-version": "2.9.33.2"
}
{
 "name": "admin/default",
 "agent-version": "2.9.33.1"
}
{
 "name": "admin/m1",
 "agent-version": "2.9.33.2"
}

$ juju models -c target --format json | jq '.models[] | {name,"agent-version"}'
{
 "name": "admin/controller",
 "agent-version": "3.0.0.1"
}
{
 "name": "admin/default",
 "agent-version": "3.0.0.1"
}

$ juju migrate k1:m1 target
ERROR source prechecks failed: cannot migrate to controller ("3.0.0.1") due to issues:
"admin/m1":
- LXD version has to be "5.2.0" at least, but current version is "5.0.0"

```

## Documentation changes

No

## Bug reference

https://bugs.launchpad.net/juju/+bug/1981955

Correct "snap install juju-db" channel to get Mongo 4.4