fix missing .pl file for singleton test case and move .pl files under <testcase>.in/

follow up to #2205

tests/scryer/cli/issues/do_not_duplicate_path_components.stdin

@@ -1,3 +1,3 @@
-['tests/scryer/cli/issues/do_not_duplicate_path_components.pl'].
-['tests/scryer/cli/issues/do_not_duplicate_path_components.pl'].
+['throw_e.pl'].
+['throw_e.pl'].
 halt.

tests/scryer/cli/issues/goals_compound_goal.toml

@@ -1,2 +1,2 @@
 # issue 820
-args = ["-f", "--no-add-history", "-g", "test,halt", "tests/scryer/cli/issues/goals.pl"]
+args = ["-f", "--no-add-history", "-g", "test,halt", "goals.pl"]

tests/scryer/cli/issues/goals_multiple_goals.in/goals.pl

@@ -0,0 +1,3 @@
+test :- write(world), nl.
+
+:- initialization(write(hello)).

tests/scryer/cli/issues/goals_multiple_goals.toml

@@ -1,2 +1,2 @@
 # issue 820
-args = ["-f", "--no-add-history", "-g", "test", "-g", "halt", "tests/scryer/cli/issues/goals.pl"]
+args = ["-f", "--no-add-history", "-g", "test", "-g", "halt", "goals.pl"]

tests/scryer/cli/issues/occurs_check_flag.toml

@@ -1,2 +1,2 @@
 # issue 841
-args = ["-f", "--no-add-history", "tests/scryer/cli/issues/occurs_check_flag.pl"]
+args = ["-f", "--no-add-history", "occurs_check_example.pl"]

tests/scryer/cli/issues/op3.toml

@@ -1,2 +1,2 @@
 # issue 839
-args = ["-f", "--no-add-history", "tests/scryer/cli/issues/op3.pl", "-g", "halt"]
+args = ["-f", "--no-add-history", "op3.pl", "-g", "halt"]

tests/scryer/cli/issues/singleton_warning.in/singleton_example.pl

@@ -0,0 +1,4 @@
+% hello
+% line!
+
+a :- b(X).

tests/scryer/cli/issues/singleton_warning.stdin

@@ -1,2 +1,2 @@
-['tests/scryer/cli/issues/issue812-singleton-warning.pl'].
+['singleton_example.pl'].
 halt.

tests/scryer/cli/issues/singleton_warning.stdout

@@ -1,2 +1,2 @@
-Warning: singleton variables X at line 4 of issue812-singleton-warning.pl
+Warning: singleton variables X at line 4 of singleton_example.pl
    true.