Whitespace fixup.
Handle final corner cases in wiki account creation and refactor

[#61261016]
Use the staging wiki, not the production one

[#61261016]
Add link to the root of the wiki to "user exists" email

[#61261016]
Only message users who we can actually make a linked account for

[#61261016]
Fix trivial mistakes

[#61261016]
Propagate errors in wiki account creation to the form

[#61261016]
Remove debugging code

[#61261016]
Fix incorrect call to urlencode

[#61261016]
Only show the wiki account preference tab if the user has an email

[#61261016]