AS the debate over affirmative action heats up, a concerted effort will be made to convince women that they are victims of job discrimination.  Currently, a constitutional initiative in California, headed for the November 1996 ballot, threatens to abolish public-sector preference programs, and, indeed, opponents of the initiative are appealing to women to oppose it. The National Organization for Women (NOW), for example, has made defeating the California Civil Rights Initiative (CCRI) its number one priority for 1996, and such formerly non-political groups as the YWCA have joined the charge to defeat it.