feat: add support for cloud agent plugins

[kral2]

This change adds a new input variable var.cloud_agent_plugins type map(string). It allows to individually enable or disable an Oracle Cloud Agent plugin.

This new input is optional for the module user. If no value is provided, the following default will be applied:

  {
    autonomous_linux       = "ENABLED"
    bastion                = "ENABLED"
    block_volume_mgmt      = "DISABLED"
    custom_logs            = "ENABLED"
    management             = "DISABLED"
    monitoring             = "ENABLED"
    osms                   = "ENABLED"
    run_command            = "ENABLED"
    vulnerability_scanning = "ENABLED"
  }

Fixes: #17

# ! provider seems to have a bug with plugin_config the stanza
// the configuration is applied at first resource creation
// subsequent updates are detected as changes by Terraform but seems to be ignored by oci provider.