Add type embedding

[amcadmus]

• add type embedding
• refact descriptor se_e2_a
• refact fitting ener

[codecov-commenter]

Codecov Report

Merging #581 (73482ac) into devel (0d0cb77) will increase coverage by 0.73%.
The diff coverage is 88.63%.

@@            Coverage Diff             @@
##            devel     #581      +/-   ##
==========================================
+ Coverage   62.09%   62.82%   +0.73%     
==========================================
  Files          74       75       +1     
  Lines        6229     6333     +104     
==========================================
+ Hits         3868     3979     +111     
+ Misses       2361     2354       -7     

Impacted Files	Coverage Δ
deepmd/utils/argcheck.py	16.36% <16.66%> (-0.18%)	⬇️
deepmd/train/trainer.py	38.84% <80.00%> (+0.52%)	⬆️
deepmd/descriptor/se_a.py	90.57% <86.20%> (+1.60%)	⬆️
deepmd/fit/ener.py	93.29% <98.14%> (+7.66%)	⬆️
deepmd/model/ener.py	90.72% <100.00%> (+0.39%)	⬆️
deepmd/utils/network.py	96.36% <100.00%> (+0.06%)	⬆️
deepmd/utils/type_embed.py	100.00% <100.00%> (ø)
deepmd/utils/data.py	90.63% <0.00%> (+0.45%)	⬆️
... and 1 more

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