Improve 'Privacy' section in profile settings

[n0toose]

• Improve "Hide the activity from the profile page" label
• E-Mail privacy icon in user profile now redirects to Privacy section
• E-Mail privacy settings moved to Privacy section

Previously, the user was redirected to the setting itself, however,
that is not a good design choice because the setting itself would
be at the very top of the user's browser window. This fix doesn't
fix the problem entirely, but it is definitely an improvement
compared to its previous iteration.

[n0toose]

I find this change to make more sense, as it brings everything together in one place and if the user decides to e.g. click on the lock icon in the profile, they get to see other privacy-related settings as well.

However, it feels a bit odd, as this checkbox appears at the very top of the screen and not at the place that the user is looking at; do I redirect them to the Privacy section (push new commit), or that specific setting (do nothing)?

EDIT: I went for the new commit. I'm not planning to increase the scope of this PR any further.

[silverwind]

Just edit the original comment description please, it will be fully preserved in the commit message on merge and it's semi-important that this info is part of the commit.

[wxiaoguang]

Overall LGTM except the nit.