feat: add benchmark for recursively listing files

[coveralls]

Pull Request Test Coverage Report for Build 4919784962

• 34 of 34 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 87.471%

---

Totals
Change from base Build 4137245146:	0.2%
Covered Lines:	1522
Relevant Lines:	1740

---

💛 - Coveralls

[alistaire47]

To get the tests passing I think you just need to do conbench list > benchmarks.json to regenerate the metadata

[westonpace]

To get the tests passing I think you just need to do conbench list > benchmarks.json to regenerate the metadata

Done.