Python: Add non-alert data for lines of code

`py/summary/lines-of-code` is just a port of the C++/JS queries added in:

- https://github.com/github/codeql/pull/5271 (C++)
- https://github.com/github/codeql/pull/5304 (JS)

We are the first to implement the `lines-of-user-code` query, so nothing to
compare with in other languages -- but it makes a lot of sense to do for Python 👍

python/ql/src/Summary/LinesOfCode.ql

@@ -0,0 +1,13 @@
+/**
+ * @id py/summary/lines-of-code
+ * @name Total lines of Python code in the database
+ * @description The total number of lines of Python code across all files, including
+ *   external libraries and auto-generated files. This is a useful metric of the size of a
+ *   database. This query counts the lines of code, excluding whitespace or comments.
+ * @kind metric
+ * @tags summary
+ */
+
+import python
+
+select sum(Module m | | m.getMetrics().getNumberOfLinesOfCode())

python/ql/src/Summary/LinesOfUserCode.ql

@@ -0,0 +1,21 @@
+/**
+ * @id py/summary/lines-of-user-code
+ * @name Total lines of user written Python code in the database
+ * @description The total number of lines of Python code from the source code directory,
+ *   excluding auto-generated files. This query counts the lines of code, excluding
+ *   whitespace or comments. Note: If external libraries are included in the codebase
+ *   either in a checked-in virtual environment or as vendored code, that will currently
+ *   be counted as user written code.
+ * @kind metric
+ * @tags summary
+ */
+
+import python
+import semmle.python.filters.GeneratedCode
+
+select sum(Module m |
+    exists(m.getFile().getRelativePath()) and
+    not m.getFile() instanceof GeneratedFile
+  |
+    m.getMetrics().getNumberOfLinesOfCode()
+  )