Custom workspace backup policies

[JC-wk]

Is your feature request related to a problem? Please describe.
Backup policies in the base workspace are currently hard coded and non-configurable.

Describe the solution you'd like
I'd like to have the option to define custom backup policies when deploying a workspace.

Describe alternatives you've considered
Modifying the template to add more backup policies and a drop down to select them.
A separate file defining custom backup policies that could be read by the terraform

Additional context
templates/workspaces/base/terraform/backup/backup.tf

resource "azurerm_backup_policy_vm" "vm_policy" {
  name                = local.vm_backup_policy_name
  resource_group_name = var.resource_group_name
  recovery_vault_name = azurerm_recovery_services_vault.vault.name


  timezone = "UTC"

  backup {
    frequency = "Daily"
    time      = "22:00"
  }

  retention_daily {
    count = 14
  }

  retention_weekly {
    count    = 4
    weekdays = ["Sunday"]
  }

  retention_monthly {
    count    = 12
    weekdays = ["Monday"]
    weeks    = ["First"]
  }

  retention_yearly {
    count    = 2
    months   = ["December"]
    weekdays = ["Sunday"]
    weeks    = ["Last"]
  }

  depends_on = [
    azurerm_recovery_services_vault.vault
  ]


}

resource "azurerm_backup_policy_file_share" "file_share_policy" {
  name                = local.fs_backup_policy_name
  resource_group_name = var.resource_group_name
  recovery_vault_name = azurerm_recovery_services_vault.vault.name

  timezone = "UTC"

  backup {
    frequency = "Daily"
    time      = "23:00"
  }

  retention_daily {
    count = 14
  }

  retention_weekly {
    count    = 4
    weekdays = ["Sunday"]
  }

  retention_monthly {
    count    = 12
    weekdays = ["Monday"]
    weeks    = ["First"]
  }

  retention_yearly {
    count    = 2
    months   = ["December"]
    weekdays = ["Sunday"]
    weeks    = ["Last"]
  }

  depends_on = [
    azurerm_recovery_services_vault.vault
  ]

}