chore: deprecate type field for boundary_account_ldap

[elimt]

The boundary_account_ldap resource has a required type field but the only valid value is "ldap". Deprecating the type field and setting a default value of ldap.

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 ldap.

resource "boundary_account_ldap" "foo" {
   name           = "test name"
   description    = "test description"
   login_name     = "foo"
   auth_method_id = boundary_auth_method_ldap.foo.id
}

A similar change for boundary_account_password: #396

[jimlambrt]

ty!