gh-113317: Clean up Argument Clinic global namespace (#113414)

Split up clinic.py by establishing libclinic as a support package for
Argument Clinic. Get rid of clinic.py globals by either making them
class members, or by putting them into libclinic.

- Move INCLUDE_COMMENT_COLUMN to BlockPrinter
- Move NO_VARARG to CLanguage
- Move formatting helpers to libclinic
- Move some constants to libclinic (and annotate them as Final)

Author: erlend-aasland

Lib/test/test_clinic.py

@@ -16,6 +16,7 @@
 
 test_tools.skip_if_missing('clinic')
 with test_tools.imports_under_tool('clinic'):
+    import libclinic
     import clinic
     from clinic import DSLParser
 
@@ -3761,19 +3762,19 @@ def test_normalize_snippet(self):
                 actual = clinic.normalize_snippet(snippet, indent=indent)
                 self.assertEqual(actual, expected)
 
-    def test_quoted_for_c_string(self):
+    def test_escaped_docstring(self):
         dataset = (
             # input,    expected
-            (r"abc",    r"abc"),
-            (r"\abc",   r"\\abc"),
-            (r"\a\bc",  r"\\a\\bc"),
-            (r"\a\\bc", r"\\a\\\\bc"),
-            (r'"abc"',  r'\"abc\"'),
-            (r"'a'",    r"\'a\'"),
+            (r"abc",    r'"abc"'),
+            (r"\abc",   r'"\\abc"'),
+            (r"\a\bc",  r'"\\a\\bc"'),
+            (r"\a\\bc", r'"\\a\\\\bc"'),
+            (r'"abc"',  r'"\"abc\""'),
+            (r"'a'",    r'"\'a\'"'),
         )
         for line, expected in dataset:
             with self.subTest(line=line, expected=expected):
-                out = clinic.quoted_for_c_string(line)
+                out = libclinic.docstring_for_c_string(line)
                 self.assertEqual(out, expected)
 
     def test_format_escape(self):
@@ -3784,7 +3785,7 @@ def test_format_escape(self):
 
     def test_indent_all_lines(self):
         # Blank lines are expected to be unchanged.
-        self.assertEqual(clinic.indent_all_lines("", prefix="bar"), "")
+        self.assertEqual(libclinic.indent_all_lines("", prefix="bar"), "")
 
         lines = (
             "one\n"
@@ -3794,7 +3795,7 @@ def test_indent_all_lines(self):
             "barone\n"
             "bartwo"
         )
-        out = clinic.indent_all_lines(lines, prefix="bar")
+        out = libclinic.indent_all_lines(lines, prefix="bar")
         self.assertEqual(out, expected)
 
         # If last line is empty, expect it to be unchanged.
@@ -3810,12 +3811,12 @@ def test_indent_all_lines(self):
             "bartwo\n"
             ""
         )
-        out = clinic.indent_all_lines(lines, prefix="bar")
+        out = libclinic.indent_all_lines(lines, prefix="bar")
         self.assertEqual(out, expected)
 
     def test_suffix_all_lines(self):
         # Blank lines are expected to be unchanged.
-        self.assertEqual(clinic.suffix_all_lines("", suffix="foo"), "")
+        self.assertEqual(libclinic.suffix_all_lines("", suffix="foo"), "")
 
         lines = (
             "one\n"
@@ -3825,7 +3826,7 @@ def test_suffix_all_lines(self):
             "onefoo\n"
             "twofoo"
         )
-        out = clinic.suffix_all_lines(lines, suffix="foo")
+        out = libclinic.suffix_all_lines(lines, suffix="foo")
         self.assertEqual(out, expected)
 
         # If last line is empty, expect it to be unchanged.
@@ -3841,7 +3842,7 @@ def test_suffix_all_lines(self):
             "twofoo\n"
             ""
         )
-        out = clinic.suffix_all_lines(lines, suffix="foo")
+        out = libclinic.suffix_all_lines(lines, suffix="foo")
         self.assertEqual(out, expected)