Allow Lua console on protected module pages

Lua debugging console is useful even if the module page is protected,
so we should display it on read-only edit pages.

However, the EditPage::showReadOnlyForm::initial hook does not allow
to insert HTML below the textarea, so we let the JS do it client-side.
(In fact, it might be a good idea to do the same in the base case
and never send the HTML from server, I guess.)

Bug: T93902
Change-Id: I953c4313fc67c6e708b5ef68db5380991a75b363