[library render]: Sanitize generated filenames

[lorentey]

Prevent reasonable chart titles such as std::deque<int> append/remove from generating invalid filenames when rendering libraries on Windows.

Checklist

• [X] I've read the Contribution Guidelines
• [X] My contributions are licensed under the Swift license.
• [X] I've followed the coding style of the rest of the project.
• [X] I've added tests covering my changes (if appropriate).
• [X] I've verified that my change compiles and works correctly, and does not break any existing tests.
• [ ] I've updated the documentation (if appropriate).

[lorentey]

Cc @compnerd, @SDGGiesbrecht -- this is a step towards being able to run benchmarks on Windows.

[lorentey]

@swift-ci test