Rename hydra heads

[lbluque]

The current code has specific names for energy and forces heads along with the keys in the prediction results.

This makes it a bit convoluted to use existing heads for another valid property. For example using the EquiformerV2EnergyHead to predict another scalar property. As it is now, we can achieve this by miss-labeling outputs and dataset targets as "energy".

This PR renames prediction heads more broadly (ie Energy -> Scalar, Forces -> Vector, etc). It also adds an output_name attribute to heads so that the prediction dictionary can be set to return arbitrary property names

[lbluque]

This is WIP, I have only renamed the EqV2 heads, but please go ahead and have a look and provide comments/suggestions and I can rename/edit all other heads

[codecov]

Codecov Report

Attention: Patch coverage is 79.14110% with 68 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/fairchem/core/_cli_hydra.py	75.00%	16 Missing ⚠️
src/fairchem/core/common/utils.py	69.04%	13 Missing ⚠️
src/fairchem/core/common/distutils.py	53.84%	12 Missing ⚠️
.../fairchem/core/scripts/convert_hydra_to_release.py	71.79%	11 Missing ⚠️
...fairchem/core/models/equiformer_v2/heads/scalar.py	84.84%	5 Missing ⚠️
src/fairchem/core/components/runner.py	84.00%	4 Missing ⚠️
...em/core/models/equiformer_v2/eqv2_to_eqv2_hydra.py	75.00%	3 Missing ⚠️
...fairchem/core/models/equiformer_v2/heads/vector.py	90.00%	3 Missing ⚠️
...m/core/common/relaxation/optimizers/lbfgs_torch.py	0.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
src/fairchem/core/_cli.py	68.11% <100.00%> (ø)
src/fairchem/core/common/flags.py	100.00% <100.00%> (ø)
...airchem/core/models/equiformer_v2/equiformer_v2.py	79.51% <100.00%> (-1.06%)	⬇️
...irchem/core/models/equiformer_v2/heads/__init__.py	100.00% <100.00%> (ø)
.../fairchem/core/models/equiformer_v2/heads/rank2.py	100.00% <100.00%> (ø)
...core/models/equiformer_v2/weight_initialization.py	100.00% <100.00%> (ø)
...m/core/common/relaxation/optimizers/lbfgs_torch.py	15.75% <0.00%> (ø)
...em/core/models/equiformer_v2/eqv2_to_eqv2_hydra.py	92.72% <75.00%> (-5.24%)	⬇️
...fairchem/core/models/equiformer_v2/heads/vector.py	90.00% <90.00%> (ø)
src/fairchem/core/components/runner.py	84.00% <84.00%> (ø)
... and 5 more

... and 6 files with indirect coverage changes

[rayg1234]

should we just add @registry.register_model("equiformer_v2_energy_head") on top of EqV2ScalarHead so that we dont need this extra class?

[lbluque]

I left the additional deprecated classes for configs that specified the module path (ie model: fairchem.core.models.equiformer_v2.equiformer_v2.EquiformerV2EnergyHead).

If we dont mind just breaking backwards compatibility, I'd say then remove the deprecated classes here, and the name from the registry as well

[rayg1234]

oh ic, ok let's leave but lets remember to remove it in a future cleanup task then