Enable SUL account support and permit editing on talk pages, user pages, and translations.
# Migration plan
[X] Restrict editing on GovWiki to editors as previously discussed (needed, as the next step will let random people in)
[ ] Enable CentralAuth extension, allowing local account holders to log in (this is disabled on normal wikis, but we want it enabled at GovWiki for some short transitional/migration period)
[ ] Inform all enabled account holders CentralAuth is available. Offer them the possibility to manually merge their account via Special:MergeAccount if they want to, making it clear it will be eventually done by us (well, me). This is not a strictly required step, however, I personally prefer having control over when migration for my account happens, so I thought it's good to give notice and a possibility for self-service if someone wants to.
[ ] Wait 7 days
[ ] Merge all existing accounts to (some) global account. Since that process is hard to explain using text-only, there's [a diagram](https://drive.google.com/file/d/1dMw76eMWvovjhW-53Xa-suSmpzZnfVJH/view?usp=sharing) for it. Green blocks in the diagram are actions I can do myself, actions that need to be assisted by someone else are in orange.
[ ] Ensure there are no left unmigrated accounts.
[ ] Disable logging in via local account credentials (this is to make GovWiki's behavior same as behavior of all other SUL wikis; local credentials were temporarily kept enabled for transitional purposes as part of step 2).