[Change Proposal] Add destination index aliases to Transform spec and required _meta fields

An additional property was added to Transform destination index settings thanks to https://github.com/elastic/elasticsearch/pull/94943. Users can now add `aliases` to specify optional index aliases that are associated with the destination index.

[The spec for Transform](https://github.com/elastic/package-spec/blob/main/spec/integration/elasticsearch/transform/transform.spec.yml) should also be updated to allow this new property. An example of what the new spec should support:

Elasticsearch:
```json
{
...
"dest": {
"index": "my-transform-dest",
"aliases": [
{
"alias": "my-dest-alias-1"
},
{
"alias": "my-dest-alias-2",
"move_on_creation": true
}
]
},
...
```

Additionally, we want to reinforce some new fields in the transform spec's _meta, specifically the fleet_transform_version.
```yml
_meta:
# (ideally required) version of the transform, default will be treated as 0.1.0
# if transform version doesn't change across package version upgrades or downgrades, it will not be reinstalled again
fleet_transform_version: 0.2.0
# (optional) order of which transform whould created and started, in relation to other transforms in the package
order: 2
# (optional) if transform should be installed as kibana_system user, or with secondary authorization from Kibana user
# default will be treated as true
run_as_kibana_system: false
```