[Feature] Add option to deactivate email in livechat

[janrudolph]

Due to privacy concerns, some livechat managers do not like to store any structured user data like email in livechat. Hence, there should be an option to deactivate the email input field in the livechat registration form.

Acceptance criteria:

• When registering in livechat, an user does not have to specify an email address.
• The livechat admin is able to activate / deactivate the input field.

[sampaiodiego]

while we don't have a better page to configure pre-chat form fields, I was thinking in just having a toggle to disable the fields we current have.. I was thinking something like this, separate the current "livechat appearance" screen into three major groups (with an accordion style component), what do you think?

[snake-py]

How can I deactivate emails for registration completely?