Unfortunately no, not yet. The same request appeared on this forum long ago: Escaping % or _ in the table filter,
then was logged as a feature request on the SQL Developer Exchange...
http://sqldeveloper.oracle.com -> Feature Requests -> Search using the two row filters: 'escape' and 'filter '
and eventually that generated an Enhancement Request: Bug 8315912 - ESCAPE CHARACTER OPTION IN FILTER DIALOGUE
I was hoping that the Worksheet set escape '<escapeChar>' feature would help, but it is apparently ignored in the worksheet
(for that I logged Bug 17539739 - SET ESCAPE IS IGNORED)
and even if it worked there, it might not have any effect on the Connection Navigator tree.
In the worksheet, this works...
select table_name from tabs where table_name like '%\_A' ESCAPE '\';
but not this...
set escape '\'
select table_name from tabs where table_name like '%\_A';