feat: Add boundary_auth_method data source

[moduli]

This PR adds a boundary_auth_method data source

data "boundary_auth_method" "auth_method" {
  name = "password_auth_method"
}

data "boundary_auth_method" "auth_method" {
  name     = "password_auth_method"
  scope_id = data.boundary_scope.org.id
}

Test

resource "boundary_auth_method_password" "ampw_org" {
  depends_on = [boundary_scope.org]
  name       = "test"
  type       = "password"
  scope_id   = boundary_scope.org.id
}

data "boundary_auth_method" "ampw_org" {
  depends_on = [boundary_auth_method_password.ampw_org]
  name       = "test"
  scope_id   = boundary_scope.org.id
}

output "test" {
  value = data.boundary_auth_method.ampw_org
}

Outputs:

authmethodpw = {
  "description" = ""
  "id" = "ampw_NMMfq7mf6B"
  "name" = "test"
  "scope" = tolist([
    {
      "description" = ""
      "id" = "o_59SPGMyVfV"
      "name" = "org"
      "parent_scope_id" = "global"
      "type" = "org"
    },
  ])
  "scope_id" = "o_59SPGMyVfV"
  "type" = "password"
}

[elimt]

What do you think about reading the attributes field? Could be useful for LDAP & OIDC auth methods which shows the URLs, states, etc. The fields are different for each auth method

[moduli]

Can take a look at it.

[elimt]

We can also do it in later enhancements