Swift: prepare integration tests for internal running

This harmonizes Swift integration tests with the rest of the repository,
to prepare for the internal integration test runner to run them. The
stripped down runner is kept compatible, so that current CI can still
use it now. Maybe it will be kept for developer use.

This PR includes:
* moving the integration tests inside `ql`
* editing `qlpack.yml` so that the internal runner can use it
* change database directory to be `test-db` rather than `db`

swift/ql/integration-tests/create_database_utils.py

@@ -0,0 +1,41 @@
+"""
+Simplified version of internal `create_database_utils.py` used to run the tests locally, with
+minimal and swift-specialized functionality
+TODO unify integration testing code across the public and private repositories
+"""
+import subprocess
+import pathlib
+import sys
+import shutil
+
+
+def runSuccessfully(cmd):
+    res = subprocess.run(cmd)
+    if res.returncode:
+        print("FAILED", file=sys.stderr)
+        print(" ", *cmd, f"(exit code {res.returncode})", file=sys.stderr)
+        sys.exit(res.returncode)
+
+def runUnsuccessfully(cmd):
+    res = subprocess.run(cmd)
+    if res.returncode == 0:
+        print("FAILED", file=sys.stderr)
+        print(" ", *cmd, f"(exit code 0, expected to fail)", file=sys.stderr)
+        sys.exit(1)
+
+
+def run_codeql_database_create(cmds, lang, keep_trap=True, db=None, runFunction=runSuccessfully):
+    """ db parameter is here solely for compatibility with the internal test runner """
+    assert lang == 'swift'
+    codeql_root = pathlib.Path(__file__).parents[3]
+    shutil.rmtree("test-db", ignore_errors=True)
+    cmd = [
+        "codeql", "database", "create",
+        "-s", ".", "-l", "swift", f"--search-path={codeql_root}", "--no-cleanup",
+    ]
+    if keep_trap:
+        cmd.append("--keep-trap")
+    for c in cmds:
+        cmd += ["-c", c]
+    cmd.append("test-db")
+    runFunction(cmd)