Add `is_primary_for_scope` attribute to `boundary_auth_method_password` resource

[rayennh]

Currently, the boundary_auth_method_password resource does not have an attribute to mark the auth method as the primary method for its scope.

As a result, the only way to make a password auth method primary is to activate it outside of Terraform. Until then, when using Boundary via the CLI, the user must explicitly provide the auth method ID to authenticate, which is inconvenient and reduces the usability of the CLI.

Potential Terraform Configuration

resource "boundary_auth_method_password" "password" {
  scope_id = boundary_scope.org.id
  is_primary_for_scope = true
}