**Description**

Replace the Configuration JSON text-area with a form that has individual input fields for each key & value. This will remove the need for the user to provide a json object. See hashicorp vault's key-value secrets UI for an example of what this might look like:

![Screenshot 2020-09-21 at 12 06 03](https://user-images.githubusercontent.com/17148324/93759844-df04f680-fc02-11ea-8613-f3bcc0b22d09.png)
 
- If present these keys and values should be serialised as json client-side and posted to the trigger-dag API endpoint as the `conf` request-parameter.
- By default no conf request-parameter is sent. Perhaps a checkbox should be used to determine whether conf is sent at all?
- The user may want to add new keys, or remove keys & values that they have previously added.
- [PR-10839](https://github.com/apache/airflow/pull/10839) is pre-populating the form with the DAG's default params. The new form should be pre-populated with the keys & values from `DAG.params`


**Use case / motivation**

Currently when triggering a manual DAG run with user-provided runtime parameters, the user has to provide a correctly formatted JSON object. Filling in a form with keys & values will be a significantly better user experience, and will be less error prone & laborious than handling json in a free-text field.

This builds on the great work already done on enhancing the Trigger-DAG functionality

**Related Issues**

Originating PR: https://github.com/apache/airflow/pull/10839
"""Base View to set Airflow related properties"""
    from airflow import macros
    route_base = ""
    extra_args = {
        
        "macros": macros,
        "get_docs_url": get_docs_url,
    }
    if not conf.getboolean("core", "unit_test_mode"):
        extra_args["sqlite_warning"] = settings.engine.dialect.name == "sqlite"
        extra_args["sequential_executor_warning"] = conf.get("core", "executor") == "SequentialExecutor"
    line_chart_attr = {
        "legend.maxKeyLength": 200,
    }
    def render_template(self, *args, **kwargs):
        
        if TriggererJob.is_needed():
            kwargs["triggerer_job"] = lazy_object_proxy.Proxy(TriggererJob.most_recent_job)
        return super().render_template(
            *args,
            
            scheduler_job=lazy_object_proxy.Proxy(SchedulerJob.most_recent_job),
            **kwargs,
        )
class Airflow(AirflowBaseView):
    """Main Airflow application."""
    @expose("/health")
    def health(self):