**Description**

Although the changes to FAB that include the [syncing of roles on login](https://github.com/dpgaspar/Flask-AppBuilder/commit/dbe1eded6369c199b777836eb08d829ba37634d7) hasn't been officially released, I'm proposing that we make some changes to the [airflow configmap](https://github.com/apache/airflow/blob/master/chart/templates/configmaps/configmap.yaml) in preparation for it.

Currently, this configmap contains the `airflow.cfg`, `webserver_config.py`, `airflow_local_settings.py`, `known_hosts`, `pod_template_file.yaml`, and the `krb5.conf`. With all of these tied together, changes to any of the contents across the listed files will force a restart for the flower deployment, scheduler deployment, worker deployment, and the webserver deployment through the setting of the `checksum/airflow-config` in each. 

The reason I would like to split out at _least_ the `webserver_config.py` from the greater configmap is that I would like to have the opportunity to make incremental changes to the [AUTH_ROLES_MAPPING](https://github.com/dpgaspar/Flask-AppBuilder/blob/dbe1eded6369c199b777836eb08d829ba37634d7/docs/config.rst#configuration-keys) in that config without having to force restarts for all of the previously listed services apart from the webserver.  Currently, if I were to add an additional group mapping that has no bearing on the workers/schedulers/flower these services would incur some down time despite not even mounting in this specific file to their pods.
chart/tests/test_webserver_deployment.py
docs = render_chart(
            values={
                "config": {
                    "webserver": {"base_url": "https://example.com:21222/mypath/path"},
                }
            },
            show_only=["templates/webserver/webserver-deployment.yaml"],
        )
        assert (
            jmespath.search("spec.template.spec.containers[0].livenessProbe.httpGet.path", docs[0])
            == "/mypath/path/health"
        )
        assert (
            jmespath.search("spec.template.spec.containers[0].readinessProbe.httpGet.path", docs[0])
            == "/mypath/path/health"
        )
    def test_should_not_contain_host_header_if_host_empty_string(self):
        docs = render_chart(
            values={},
            show_only=["templates/webserver/webserver-deployment.yaml"],
        )
        assert (
            jmespath.search("spec.template.spec.containers[0].livenessProbe.httpGet.httpHeaders", docs[0])
            is None
        )
        assert (
            jmespath.search("spec.template.spec.containers[0].readinessProbe.httpGet.httpHeaders", docs[0])
            is None
        )
    def test_should_not_contain_host_header_if_base_url_not_set(self):