Author: Paul Holden
MDL-82938 reportbuilder: update column editor sorting icons.
Clarify language strings for the same; remove some duplication from
accompanying tests.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=0ba1e78bcf9c0c8f752d9347ab045c06d5acc50f
http://github.com/moodle/moodle/commit/0ba1e78bcf9c0c8f752d9347ab045c06d5acc50f
+ 4.5 en [columnsortdirectionasc,core_reportbuilder]
+ 4.5 en [columnsortdirectiondesc,core_reportbuilder]