Don't persist unsaved values on Avatar picker dialog

[erdemyerebasmaz]

When Avatar name & icon are randomized but then user cancels their changes on Avatar picker dialog, their values persist the next time Avatar dialog is shown.

For example, if the user goes through the flow mentioned above and then later decides to upload a new avatar image. They are very likely to end up with the randomized user name on the first flow they cancelled.

https://github.com/breez/breezmobile/assets/4012752/c2ffade7-8e80-4460-b4c1-2cf319ea4a28