initial support for metrics as loss functions

[codecov-commenter]

Codecov Report

Base: 72.82% // Head: 72.84% // Increases project coverage by +0.02% :tada:

Coverage data is based on head (45019c6) compared to base (6d7f4d0). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #75 +/- ## ========================================== + Coverage 72.82% 72.84% +0.02% ========================================== Files 73 73 Lines 5064 5068 +4 Branches 1039 1039 ========================================== + Hits 3688 3692 +4 Misses 1036 1036 Partials 340 340 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `72.79% <100.00%> (+0.02%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Arjun+Desai#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://codecov.io/gh/ad12/meddlr/pull/75?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Arjun+Desai) | Coverage Δ | | |---|---|---| | [meddlr/metrics/lpip.py](https://codecov.io/gh/ad12/meddlr/pull/75/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Arjun+Desai#diff-bWVkZGxyL21ldHJpY3MvbHBpcC5weQ==) | `79.66% <100.00%> (+0.71%)` | :arrow_up: | | [meddlr/metrics/ssfd.py](https://codecov.io/gh/ad12/meddlr/pull/75/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Arjun+Desai#diff-bWVkZGxyL21ldHJpY3Mvc3NmZC5weQ==) | `92.00% <100.00%> (+0.16%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Arjun+Desai). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Arjun+Desai)

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