Patch eval metrics to markdown

[EricLiclair]

• adds changes to return metrics from evals
• prints converted metrics to markdown

TODO's: Collect metrics over the whole benchmark:

• • [ ] online,
• • [x] knn,
• • [x] linear, and
• • [x] finetune eval
• [x] Print metrics at end of benchmark script (currently only printing the converted markdown)
• [x] Optional: Print also as markdown table

---

prints the results like: (values randomly generated and passed to the function)

| Eval Name | Metric Name | Value |
|:---------:|:-----------:|:-----:|
| knn       | val_top1    | 0.44  |
| knn       | val_top5    | 0.27  |
| linear    | val_top1    | 0.26  |
| linear    | val_top5    | 0.27  |
| finetune  | val_top1    | 0.68  |
| finetune  | val_top5    | 0.45  |

which prints markdown like,

Eval Name	Metric Name	Value
knn	val_top1	0.44
knn	val_top5	0.27
linear	val_top1	0.26
linear	val_top5	0.27
finetune	val_top1	0.68
finetune	val_top5	0.45

---

potentially fixes #1333

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 84.90%. Comparing base (9578268) to head (599942d). Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1706 +/- ## ======================================= Coverage 84.90% 84.90% ======================================= Files 156 156 Lines 6526 6526 ======================================= Hits 5541 5541 Misses 985 985 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.