chore: Deprecate type field for boundary_account_password

[elimt]

The boundary_account_password resource has a required type field but the only valid value is "password." Deprecating the type field and setting a default value. Users will still be able to pass in a value for the type field. This will prevent existing configs from breaking.

Example: The missing type field will default to password.

resource "boundary_account_password" "jeff" {
 auth_method_id = boundary_auth_method.password.id
 login_name     = "jeff"
 password       = "$uper$ecure"
}

[ddebko]

This looks great