Bug 1946291: Change 'Pages and collections' to 'Portfolios'

'P/pages and collections', 'P/pages or collections', 'P/pages /
collections', 'P/pages/collections': => 'P/portfolios'

'P/page or collection', 'P/page / collection', 'P/page/collection':
=> 'P/portfolio'

I have left a few instances of 'pages and/or collections' where it
seemed more appropriate to use this terminology.

I have updated affected Behat tests and bumped lang strings

Change-Id: I601027c65983f3757024c5db2673ffca2ebfa654