* fcl-db: additional stringfilter tests



git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@26252 3ad0048d-3df7-0310-abae-a5850022a9f2
* fcl-db: dbf,bufdataset (and descendents): allow filter using double delimiters inside string. Fixes issue #25432
  allow escaping delimiters by doubling them e.g.
  Filter:='(NAME=''O''''Malley''''s "Magic" Hammer'')';
  which gives
  (NAME='O''Malley''s "Magic" Hammer')
  which will match record
  O'Malley's "Magic" Hammer



git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@26253 3ad0048d-3df7-0310-abae-a5850022a9f2