UserSettingsView: use switch for locking account

[danirabbit]

Can be rebase merged if desired

• Uses an action to manage account lock state and sensitivity
• Uses a switch instead of a text button in line with other settings panes
• Change primary tooltip text to be state agnostic. Avoids a situation where it reads "Disable Account checkbox checked" which is pretty difficult to figure out whether that means the account is disabled or not
• Make sure we use accurate secondary tooltip text

[ryonakano]

Shouldn't this be named as something like lock_switch or at least enable_switch then?

[zeebok]

Do you think the enable switch should be more aligned with the username field?