[QGIS-Developer] Processing 3.0: Dropping SelectByAttribute algorithm

[Alexander Bruy]

As part of the ongoing Processing upgrade and cleanup we should take
the opportunity to get rid of duplicated algorithms.

Now, when we have powerful "Select by expression" tool personally I see no
reasons to keep "Select by attribute" which now provides only limited susbset
of selection options. Any objections to delete "Select by attribute"?

-- 
Alexander Bruy