Split editcascadeprotected permission from protect permission

Split editcascadeprotected permission from protect permission

Currently, both permissions are summarised in the protect permission. This is
unadvantageous for wikis that want to split this permission, for example for the
main page: They don't want protection changes by non-sysop users there, but on
transcluded pages some less privileged users are allowed to edit. Currently,
it is impossible to divide these permissions in a clean way (they can add a hack
depnding on action parameter in LocalSettings.php right now). Furthermore, an
additional permission is no pain, because by default it is handled the same as
protect until now.

Note that for sakes of backwards compability I decided to handle editcascadeprotected
as a subset of protect instead of removing all permissions to edit cascadeprotected
pages (and change the cascade protection state of a page) for users who only have got
the protect permission. Furthermore a different model would raise some strange questions
about the behaivour of the protection form for users with protect, but no editcascadeprotected.

Bug: T101309
Change-Id: I0734d6c26e75d7d7c01cf9750ad0315dd2c85bef