psql: Add ignore_slash_options in bind's inactive branch

All commands accepting arguments, handling them with OT_NORMAL, OT_SQLID
or OT_SQLIDHACK, should call ignore_slash_options() in inactive branch
to scan and discard extra arguments.  All the backslash commands that
handle arguments do so, except \bind.

This commit adds the missing ignore_slash_options to \bind's inactive
branch.  This inconsistency is a logic bug, however the behavior happens
to be unchanged as any extra arguments are discarded later in
HandleSlashCmds(), so no backpatch is done.

While on it, this adds \bind to the list of backslash commands where
inactive \if branches are checked in the tests for psql.

Reported-by: Jelte Fennema-Nio
Author: Anthonin Bonnefoy
Discussion: https://postgr.es/m/CAGECzQR1+udGKz+FbHiCQ7CWDiF1fCGi2xYuvQUODdMAfJbaLA@mail.gmail.com

src/bin/psql/command.c

@@ -486,6 +486,8 @@ exec_command_bind(PsqlScanState scan_state, bool active_branch)
 		pset.bind_nparams = nparams;
 		pset.bind_flag = true;
 	}
+	else
+		ignore_slash_options(scan_state);
 
 	return status;
 }

src/test/regress/expected/psql.out

@@ -4506,6 +4506,7 @@ bar 'bar' "bar"
 	\echo `nosuchcommand` :foo :'foo' :"foo"
 	\pset fieldsep | `nosuchcommand` :foo :'foo' :"foo"
 	\a
+	SELECT $1 \bind 1 \g
 	\C arg1
 	\c arg1 arg2 arg3 arg4
 	\cd arg1

src/test/regress/sql/psql.sql

@@ -989,6 +989,7 @@ select \if false \\ (bogus \else \\ 42 \endif \\ forty_two;
 	\echo `nosuchcommand` :foo :'foo' :"foo"
 	\pset fieldsep | `nosuchcommand` :foo :'foo' :"foo"
 	\a
+	SELECT $1 \bind 1 \g
 	\C arg1
 	\c arg1 arg2 arg3 arg4
 	\cd arg1