Remove hyphens from the flow testcase generator folder name

So that it can be imported from the autogenerated query `gen.ql`

Author: atorralba

java/ql/src/utils/flow-testcase-generator/FlowTestCase.qll renamed to java/ql/src/utils/flowtestcasegenerator/FlowTestCase.qll

@@ -130,7 +130,7 @@ def qualifiedOuterNameFromCsvRow(row):
     f.write("name: test-generation-query\nversion: 0.0.0\nlibraryPathDependencies: codeql/java-queries")
 with open(qlFile, "w") as f:
     f.write(
-        "import java\nimport utils.GenerateFlowTestCase\n\nclass GenRow extends TargetSummaryModelCsv {\n\n\toverride predicate row(string r) {\n\t\tr = [\n")
+        "import java\nimport utils.flowtestcasegenerator.GenerateFlowTestCase\n\nclass GenRow extends TargetSummaryModelCsv {\n\n\toverride predicate row(string r) {\n\t\tr = [\n")
     f.write(",\n".join('\t\t\t"%s"' % spec.strip() for spec in specs))
     f.write("\n\t\t]\n\t}\n}\n")