Feature/bug: Specify a new profile picture (avatar builder only)

### User Story

As a user, I want to update to a new profile **_picture_**. https://twitter.com/owocki/status/1336580339192397824?s=20

I have one set presently and there is no way I see to do anything but use the avatar creator, no upload is avalible, although I do have one set presently: https://gitcoin.co/NukeManDan/

Here I see one of my "avitars" as my picture https://gitcoin.co/onboard/profile?steps=avatar

**Ideally this could be your https://en.gravatar.com/ *or* an upload for convenience as well.**

### Why Is this Needed

*Summary*: Not everyone wants to use an avatar 😉

### Description

[comment]: # (Feature or Bug? i.e Type: Bug)
*Type*:Feature / Bug (as I have a pic but can't change it)