add a funnel visualization type (highlight#8761)

## Summary

* Adds initial support for event funnel charts.
Funnel applies to events, grouped by `secure_session_id`, to allow
charting sessions where a number of events happen.
Once events have additional session metadata, it should be possible to
group by user rather than by session.
Currently, some of the graph configuration is disabled when the chart is
a funnel, as it is set to the
default values that the funnel querying assumes (ie. the group by /
bucket by / metric)

The funnel loads by using the `Metrics` query, sharing the query logic
with other graph types.
Multiple steps are loaded serially to allow filtering on the group
values (sessions) from the previous bar.

Closes highlight#9098
Closes HIG-4864

## How did you test this change?

<img width="1565" alt="Screenshot 2024-10-07 at 10 21 05"
src="https://github.com/user-attachments/assets/ed122c3c-0400-4017-98fd-ac5308decb48">

- [x] Switching to a funnel chart when the selected source is `events`
- [x] Adding / removing steps using event filters, setting different
titles for various steps
- [x] Saving / reloading dashboard with event filters 
- [x] Loading state for the funnel is correct, showing funnel once all
steps are loaded
- [x] UI is using correct figma designs

## Are there any deployment considerations?

no

## Does this work require review from our design team?

will review with @julian-highlight

backend/clickhouse/events.go

@@ -79,8 +79,8 @@ type SessionEventRow struct {
 	UUID             string
 	ProjectID        uint32
 	SessionID        uint64
-	SessionCreatedAt time.Time
-	Timestamp        time.Time
+	SessionCreatedAt int64
+	Timestamp        int64
 	Event            string
 	Attributes       map[string]string
 }
@@ -115,6 +115,7 @@ func (client *Client) WriteSessionEventRows(ctx context.Context, eventRows []*Se
 			NewStruct(new(SessionEventRow)).
 			InsertInto(SessionEventsTable, chEvents...).
 			BuildWithFlavor(sqlbuilder.ClickHouse)
+		eventsSql, eventsArgs = replaceTimestampInserts(eventsSql, eventsArgs, map[int]bool{3: true, 4: true}, MicroSeconds)
 
 		return client.conn.Exec(chCtx, eventsSql, eventsArgs...)
 	}

backend/clickhouse/query.go

@@ -752,14 +752,14 @@ func matchesQuery[TObj interface{}](row *TObj, config model.TableConfig, filters
 		switch filter.Operator {
 		case listener.OperatorAnd:
 			for _, childFilter := range filter.Filters {
-				if !matchesQuery(row, config, listener.Filters{childFilter}, filter.Operator) {
+				if !matchesQuery[TObj](row, config, listener.Filters{childFilter}, filter.Operator) {
 					return false
 				}
 			}
 		case listener.OperatorOr:
 			var anyMatch bool
 			for _, childFilter := range filter.Filters {
-				if matchesQuery(row, config, listener.Filters{childFilter}, filter.Operator) {
+				if matchesQuery[TObj](row, config, listener.Filters{childFilter}, filter.Operator) {
 					anyMatch = true
 					break
 				}
@@ -768,7 +768,7 @@ func matchesQuery[TObj interface{}](row *TObj, config model.TableConfig, filters
 				return false
 			}
 		case listener.OperatorNot:
-			return !matchesQuery(row, config, listener.Filters{filter.Filters[0]}, filter.Operator)
+			return !matchesQuery[TObj](row, config, listener.Filters{filter.Filters[0]}, filter.Operator)
 		default:
 			matches, err := matchFilter(row, config, filter)
 			if err != nil {
@@ -971,7 +971,6 @@ func (client *Client) ReadMetrics(ctx context.Context, input ReadMetricsInput) (
 	if len(input.MetricTypes) == 0 {
 		return nil, errors.New("no metric types provided")
 	}
-
 	if input.Params.DateRange == nil {
 		input.Params.DateRange = &modelInputs.DateRangeRequiredInput{
 			StartDate: time.Now().Add(-time.Hour * 24 * 30),
@@ -1331,7 +1330,6 @@ func (client *Client) ReadMetrics(ctx context.Context, input ReadMetricsInput) (
 
 	return metrics, err
 }
-
 func formatColumn(input string, column string) string {
 	base := input
 	if base == "" {

backend/model/model.go

@@ -1417,6 +1417,7 @@ type Graph struct {
 	Limit             *int
 	LimitFunctionType *modelInputs.MetricAggregator
 	LimitMetric       *string
+	FunnelSteps       *string `gorm:"type:jsonb"`
 	Display           *string
 	NullHandling      *string
 }