**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
logs_per_page = PAGE_SIZE
        audit_logs_count = query.count()
        num_of_pages = int(math.ceil(audit_logs_count / float(logs_per_page)))
        start = current_page * logs_per_page
        end = start + logs_per_page
        sort_column = Log.__table__.c.get(arg_sorting_key)
        if sort_column is not None:
            if arg_sorting_direction == "desc":
                sort_column = sort_column.desc()
            query = query.order_by(sort_column)
        dag_audit_logs = query.offset(start).limit(logs_per_page).all()
        return self.render_template(
            "airflow/dag_audit_log.html",
            dag=dag,
            dag_model=dag_model,
            root=request.args.get("root"),
            dag_id=dag_id,
            dag_logs=dag_audit_logs,
            num_log_from=min(start + 1, audit_logs_count),
            num_log_to=min(end, audit_logs_count),
            audit_logs_count=audit_logs_count,
            page_size=PAGE_SIZE,
            paging=wwwutils.generate_pages(
                current_page,
                num_of_pages,
            ),
            sorting_key=arg_sorting_key,
            sorting_direction=arg_sorting_direction,
        )
class ConfigurationView(AirflowBaseView):