Feature request: Support LLVM lit

[tgymnich]

It would be nice if the benchmark action could support the lit the LLVM Integrated Tester.

The json output generated by lit looks as follows:

{
  "__version__": [
    15,
    0,
    0
  ],
  "elapsed": 13.489635944366455,
  "tests": [
    {
      "code": "PASS",
      "elapsed": 13.247512102127075,
      "name": "Target :: [Target]/[TestSuite]/[TestName].ll",
      "output": "[test output ....] "
    }
  ]
}