[JUJU-3654] Added ApplicationNotFound error for better error control.

[juanmanuel-tirado]

Description

Revisit how the returned data from the ApplicationInfo was processed in order to avoid problems when applications are not found. Apart from that, add the ApplicationNotFoundError that will help to handle erroneous situations using the handleApplicationNotFoundError function. This pattern will have to be propagated to the other resources.

Additionally, I have replaced the ubuntu charms to skip the storage issue with the recent ubuntu charm.

Type of change

Please mark if proceeds.

• New resource (a new resource in the schema)
• Changed resource (changes in an existing resource)
• Logic changes in resources (the API interaction with Juju has been changed)
• Test changes (one or several tests have been changed)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Other (describe)

Environment

• Juju controller version: 2.9.42
• Terraform version: 1.3.7

QA steps

Create an application with a plan, remove the application using Juju and see how the provider finds the application to be missing and tries to recreate it.

provider "juju" {

}

resource "juju_model" "test" {
  name = "test"
}

resource "juju_application" "test" {
  model = juju_model.test.name
  name  = "test"
  charm {
    name = "tiny-bash"
  }
}

terraform init
terraform apply
juju remove-application test -m test
terraform plan

This should display the application to be added

# juju_application.test will be created
  + resource "juju_application" "test" {
      + constraints = (known after apply)
      + id          = (known after apply)
      + model       = "test"
      + name        = "test"
      + placement   = (known after apply)
      + principal   = (known after apply)
      + trust       = false
      + units       = 1

      + charm {
          + channel  = "latest/stable"
          + name     = "tiny-bash"
          + revision = (known after apply)
          + series   = (known after apply)
        }
    }

Additional notes

This change follows the suggestions of @amandahla in #205

[cderici]

This LGTM 👍