QL: add test for qlpacks, and get them to work

ql/test/callgraph/callgraph.expected

@@ -1,3 +1,4 @@
+getTarget
 | Foo.qll:5:26:5:30 | PredicateCall | Foo.qll:3:1:3:26 | ClasslessPredicate foo |
 | Foo.qll:10:21:10:25 | PredicateCall | Foo.qll:8:3:8:28 | ClassPredicate bar |
 | Foo.qll:14:30:14:40 | MemberCall | Foo.qll:10:3:10:27 | ClassPredicate baz |
@@ -8,3 +9,7 @@
 | Foo.qll:31:5:31:12 | PredicateCall | Foo.qll:24:3:24:32 | ClasslessPredicate alias0 |
 | Foo.qll:36:36:36:65 | MemberCall | file://:0:0:0:0 | replaceAll |
 | Foo.qll:38:39:38:67 | MemberCall | file://:0:0:0:0 | regexpCapture |
+| packs/src/SrcThing.qll:4:3:4:8 | PredicateCall | packs/lib/LibThing/Foo.qll:1:1:1:30 | ClasslessPredicate foo |
+| packs/src/SrcThing.qll:5:3:5:8 | PredicateCall | packs/src/SrcThing.qll:8:1:8:30 | ClasslessPredicate bar |
+dependsOn
+| packs/src/qlpack.yml:1:1:1:4 | ql-testing-src-pack | packs/lib/qlpack.yml:1:1:1:4 | ql-testing-lib-pack |

ql/test/callgraph/callgraph.ql

@@ -1,3 +1,5 @@
 import ql
 
 query AstNode getTarget(Call call) { result = call.getTarget() }
+
+query YAML::QLPack dependsOn(YAML::QLPack pack) { result = pack.getADependency() }

ql/test/callgraph/packs/lib/LibThing/Foo.qll

@@ -0,0 +1 @@
+predicate foo(int i) { i = 3 }

ql/test/callgraph/packs/lib/qlpack.yml

@@ -0,0 +1,3 @@
+name: ql-testing-lib-pack
+version: 0.1.0
+extractor: ql-test-stuff

ql/test/callgraph/packs/src/SrcThing.qll

@@ -0,0 +1,8 @@
+import LibThing.Foo
+
+query predicate test(int i) {
+  foo(i) and
+  bar(i)
+}
+
+predicate bar(int i) { i = 4 }

ql/test/callgraph/packs/src/qlpack.yml

@@ -0,0 +1,4 @@
+name: ql-testing-src-pack
+version: 0.1.0
+dependencies: 
+  ql-testing-lib-pack: "*"

tools/qltest.sh

@@ -6,6 +6,8 @@ exec "${CODEQL_DIST}/codeql" database index-files \
     --prune="**/*.testproj" \
     --include-extension=.ql \
     --include-extension=.qll \
+    --include-extension=.dbscheme \
+    --include-extension=.yml \
     --size-limit=5m \
     --language=ql \
     --working-dir=.\