[Feature] Support elasticstack_fleet_integration to install "latest" version

[dsadosky]

Is your feature request related to a problem? Please describe.
Today the elasticstack_fleet_integration resource requires a version of the integration to be installed. We should either make this paramater optional or support a version of "latest". This is required paramater and having to figure out what the latest version of each integration is not an easy task.

Describe the resource you would like to have implemented.
A clear and concise description of the API you want to target.

Describe the solution you'd like
Make the version parameter optional vs. required. Missing should install the latest available version of the integration.

Describe alternatives you've considered
Either make version optional or support a version of "latest" that installs the most current version of the integration

Additional context
Today the version parameter is required and with the pace of releases and updates as well as Serverless being updated weekly, its hard for a developer/infrastructure engineer to keep up with what is the latest version of each integration.

[tobio]

@dsadosky this can be achieved by using both the resource and data source together. The data source will track the latest available version in the target cluster, and the resource will ensure that's the installed version. For example:

data "elasticstack_fleet_integration" "tcp" {
  name    = "tcp"
}

resource "elasticstack_fleet_integration" "tcp" {
  name         = "tcp"
  version      = data.elasticstack_fleet_integration.tcp.version
  force        = true
}

I'll add this as an example to the documentation so it's clear to anyone else coming in. Adding latest version tracking into the provider itself is likely a pretty low priority given it's already achievable, albeit with a slightly larger surface area.