DensityEstimator.loss does not take `sample_dim`

[michaeldeistler]

In #1066, we had defined that log_prob and loss have the same input and output shapes:

density_estimator.log_prob(input, condition)

input: (sample_input, batch_input, *event_shape_input)
condition: (batch_condition, *event_shape_condition)
returns: (sample_input, batch_input)
raises: batch_input != batch_condition

However, for .loss, we are now removing the sample_dim. Therefore, the .loss function now has the following signature:

input: (batch_input, *event_shape_input)
condition: (batch_condition, *event_shape_condition)
returns: (batch_input)
raises: batch_input != batch_condition

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[codecov[bot]]

Codecov Report

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

Project coverage is 77.01%. Comparing base (005aeac) to head (6ae9ede).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1149 +/- ## ========================================== - Coverage 85.09% 77.01% -8.09% ========================================== Files 90 90 Lines 6649 6643 -6 ========================================== - Hits 5658 5116 -542 - Misses 991 1527 +536 ``` | [Flag](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev) | `77.01% <100.00%> (-8.09%)` | :arrow_down: | 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=sbi-dev#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev) | Coverage Δ | | |---|---|---| | [sbi/inference/snle/mnle.py](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149?src=pr&el=tree&filepath=sbi%2Finference%2Fsnle%2Fmnle.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev#diff-c2JpL2luZmVyZW5jZS9zbmxlL21ubGUucHk=) | `85.00% <ø> (-8.48%)` | :arrow_down: | | [sbi/inference/snle/snle\_base.py](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149?src=pr&el=tree&filepath=sbi%2Finference%2Fsnle%2Fsnle_base.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev#diff-c2JpL2luZmVyZW5jZS9zbmxlL3NubGVfYmFzZS5weQ==) | `93.61% <100.00%> (ø)` | | | [sbi/inference/snpe/snpe\_base.py](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149?src=pr&el=tree&filepath=sbi%2Finference%2Fsnpe%2Fsnpe_base.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev#diff-c2JpL2luZmVyZW5jZS9zbnBlL3NucGVfYmFzZS5weQ==) | `89.02% <100.00%> (ø)` | | | [sbi/neural\_nets/density\_estimators/base.py](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149?src=pr&el=tree&filepath=sbi%2Fneural_nets%2Fdensity_estimators%2Fbase.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev#diff-c2JpL25ldXJhbF9uZXRzL2RlbnNpdHlfZXN0aW1hdG9ycy9iYXNlLnB5) | `57.14% <ø> (ø)` | | | [.../neural\_nets/density\_estimators/categorical\_net.py](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149?src=pr&el=tree&filepath=sbi%2Fneural_nets%2Fdensity_estimators%2Fcategorical_net.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev#diff-c2JpL25ldXJhbF9uZXRzL2RlbnNpdHlfZXN0aW1hdG9ycy9jYXRlZ29yaWNhbF9uZXQucHk=) | `98.03% <100.00%> (ø)` | | | [...nets/density\_estimators/mixed\_density\_estimator.py](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149?src=pr&el=tree&filepath=sbi%2Fneural_nets%2Fdensity_estimators%2Fmixed_density_estimator.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev#diff-c2JpL25ldXJhbF9uZXRzL2RlbnNpdHlfZXN0aW1hdG9ycy9taXhlZF9kZW5zaXR5X2VzdGltYXRvci5weQ==) | `69.11% <100.00%> (ø)` | | | [sbi/neural\_nets/density\_estimators/nflows\_flow.py](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149?src=pr&el=tree&filepath=sbi%2Fneural_nets%2Fdensity_estimators%2Fnflows_flow.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev#diff-c2JpL25ldXJhbF9uZXRzL2RlbnNpdHlfZXN0aW1hdG9ycy9uZmxvd3NfZmxvdy5weQ==) | `62.74% <100.00%> (ø)` | | | [sbi/neural\_nets/density\_estimators/zuko\_flow.py](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149?src=pr&el=tree&filepath=sbi%2Fneural_nets%2Fdensity_estimators%2Fzuko_flow.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev#diff-c2JpL25ldXJhbF9uZXRzL2RlbnNpdHlfZXN0aW1hdG9ycy96dWtvX2Zsb3cucHk=) | `64.44% <100.00%> (ø)` | | ... and [22 files with indirect coverage changes](https://app.codecov.io/gh/sbi-dev/sbi/pull/1149/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sbi-dev)