Fix potential infinite loops in generators combined with section filter

The problem was that under specific circumstances, namely that none
of their children progressed, `GeneratorTracker` will not progress.
This was changed recently, to allow for code like this, where a
`SECTION` follows a `GENERATE` at the same level:

```cpp
SECTION("A") {}
auto a = GENERATE(1, 2);
SECTION("B") {}
```

However, this interacted badly with `SECTION` filters (`-c foo`),
as they could deactivate all `SECTION`s below a generator, and thus
stop it from progressing forever. This commit makes GeneratorTracker
check whether there are any filters active, and if they are, it checks
whether its section-children can ever run.

Fixes #2025

include/internal/catch_test_case_tracker.cpp

@@ -233,6 +233,14 @@ namespace TestCaseTracking {
             m_filters.insert( m_filters.end(), filters.begin()+1, filters.end() );
     }
 
+    std::vector<std::string> const& SectionTracker::getFilters() const {
+        return m_filters;
+    }
+
+    std::string const& SectionTracker::trimmedName() const {
+        return m_trimmed_name;
+    }
+
 } // namespace TestCaseTracking
 
 using TestCaseTracking::ITracker;