Issue title: Showing the differentiating property of an event in Funells Insights
 Issue body: ## Is your feature request related to a problem?

When creating a conversion chart with events of the same type (like `$screen`) with different parameters (like the screen name) only the event type is displayed and this makes it very hard to understand where the users are dropping off.

![image](https://user-images.githubusercontent.com/6215122/141483112-8bca1b73-4ebf-4707-9980-bd992fcbd12c.png)


## Describe the solution you'd like

Amplitude shows the event parameter in parenthesis so that it's easy to see where the user is dropping off.

![image](https://user-images.githubusercontent.com/6215122/141483679-cd7e430d-c6d7-4e58-9e24-8c53aeed44c3.png)

#### *Thank you* for your feature request – we love each and every one!

 Comments: 
 Comment 0: Thanks for this @savy-91! Makes sense to clean this up
 Comment 1: I have been thinking on how best it would be to proceed to improve this (I was thinking of creating a PR for it) and here are a couple of options (not mutually exclusive):

- Allow users to set a custom name for the step regardless of the event that is being tracked
- Display all filters (if there are) in the step either as a popover or text
- Only display filters if there is just a WHERE clause (like the Amplitude example)
 Comment 2: Oh that's awesome, thanks for the interest!

Tagging @alexkim205 who did some similar work to provide more guidance
 Comment 3: Hi @savy-91 glad you asked! There is a new feature that we're rolling out that allows you to give filters/steps custom names which I think will solve your use case here. 

We can add you to our beta testers if you'd like to try it out? If so, just let me know what your email address is so that I can add you. 
 Comment 4: > Hi @savy-91 glad you asked! There is a new feature that we're rolling out that allows you to give filters/steps custom names which I think will solve your use case here.
> 
> <img alt="Screen Shot 2021-11-15 at 8 18 15 AM" width="468" src="https://user-images.githubusercontent.com/13460330/141816510-183dc62d-8c5b-4229-837e-bc51614a9889.png">
> 
> <img alt="Screen Shot 2021-11-15 at 8 17 52 AM" width="969" src="https://user-images.githubusercontent.com/13460330/141816454-701ba576-056d-4ecc-93c1-f36e96e731b3.png">
> 
> We can add you to our beta testers if you'd like to try it out? If so, just let me know what your email address is so that I can add you.

This is exactly what I had in mind! I'd be glad to test it out. My account on Posthog-cloud is areyes@example.com
 Comment 5: Awesome! I've added you to our beta list and you should be able to see this feature on your end :) 
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