### Description

Support mounting to multiple namespaces with the Hashicorp Vault Secrets Back-end

### Use case/motivation

As a data engineer I wish to utilize secrets stored in multiple mount paths (to support connecting to multiple namespaces)  without having to mount to a higher up namespace.

### Related issues

_No response_

### Are you willing to submit a PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

mock_client = mock.MagicMock()
        mock_hvac.Client.return_value = mock_client
        with pytest.raises(VaultError, match="'token' authentication type requires 'token'"):
            _VaultClient(auth_type="token", url="http://localhost:8180")
    @mock.patch("airflow.providers.hashicorp._internal_client.vault_client.hvac")
    def test_token(self, mock_hvac):
        mock_client = mock.MagicMock()
        mock_hvac.Client.return_value = mock_client
        vault_client = _VaultClient(
            auth_type="token", token="s.7AU0I51yv1Q1lxOIg1F3ZRAS", url="http://localhost:8180"
        )
        client = vault_client.client
        mock_hvac.Client.assert_called_with(url="http://localhost:8180")
        client.is_authenticated.assert_called_with()
        assert "s.7AU0I51yv1Q1lxOIg1F3ZRAS" == client.token
        assert 2 == vault_client.kv_engine_version
        assert "secret" == vault_client.mount_point
    @mock.patch("airflow.providers.hashicorp._internal_client.vault_client.hvac")
    def test_token_path(self, mock_hvac):