Add Windows integration tests showing that subst is handled inconsistently

javascript/ql/integration-tests/subst/code/main.js

@@ -0,0 +1 @@
+function interesting() { }

javascript/ql/integration-tests/subst/code/test.ts

@@ -0,0 +1 @@
+0

javascript/ql/integration-tests/subst/file.expected

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+| file://Z:/main.js:0:0:0:0 | Z:/main.js | relative |
+| file://Z:/test.ts:0:0:0:0 | Z:/test.ts | relative |

javascript/ql/integration-tests/subst/file.ql

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+import javascript
+
+from File f, string relative
+where
+  not f.getURL().matches("%/target/intree/%") and
+  if exists(f.getRelativePath()) then relative = "relative" else relative = ""
+select f, relative

javascript/ql/integration-tests/subst/test.py

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+import runs_on
+
+
+@runs_on.windows
+def test(codeql, javascript, cwd, subst_drive):
+    drive = subst_drive(cwd / "code")
+    codeql.database.create(source_root=drive)