Implement schema for user secrets management

[anvial]

Description

This PR introduces the ability to add, update, and remove user secrets in the schema. This is done through the userSecretResource struct, which has methods for each of these actions.

Fixes:

Type of change

• Add new resource

QA steps

Check acceptance tests:

TF_ACC=1 TEST_CLOUD=lxd TF_ACC_LOG=TRACE TF_LOG=TRACE TF_ACC_LOG_PATH=/tmp/test.txt go test ./...

Example of TF plan:

terraform {
  required_providers {
    juju = {
      source  = "juju/juju"
      version = "0.11.0"
    }
  }
}
provider "juju" {}

resource "juju_secret" "my_secret" {
  model = "test"
  name  = "my_secret_name"
  value = {
    key1 = "value1"
    key2 = "value2"
  }
  info  = "This is my secret"
}

resource "juju_application" "jameinel-ubuntu-lite" {
  name  = "jameinel-ubuntu-lite"
  model = "test"


  charm {
    name     = "jameinel-ubuntu-lite"
    channel  = "latest/stable"
  }

  units = 1
}

terraform init -upgrade  && terraform plan && terraform apply -auto-approve

[hmlanigan]

Some initial thoughts and hints

[Aflynn50]

Looks good, just a few things.

[cderici]

Couple of small points noted, QA went well. Approving, but the check against 2.9 for the secrets api is needed.