Rename UserMaterial... to shorter names

[adtzlr]

old	new
UserMaterial	Material
UserMaterialStrain	MaterialStrain
UserMaterialHyperelastic	Hyperelastic

old alias names are available until the next major release

closes #482

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (5313f1d) 97.87% compared to head (de60fc9) 97.88%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #483   +/-   ##
=======================================
  Coverage   97.87%   97.88%           
=======================================
  Files          84       84           
  Lines        3913     3916    +3     
=======================================
+ Hits         3830     3833    +3     
  Misses         83       83           

Impacted Files	Coverage Δ
src/felupe/_assembly/_axi.py	97.46% <ø> (ø)
src/felupe/_assembly/_base.py	96.92% <ø> (ø)
src/felupe/_assembly/_form.py	74.56% <ø> (ø)
src/felupe/_assembly/_mixed.py	97.01% <ø> (ø)
src/felupe/_basis/_basis.py	90.00% <ø> (ø)
src/felupe/_field/_base.py	92.56% <ø> (ø)
src/felupe/_field/_container.py	100.00% <ø> (ø)
src/felupe/constitution/_mixed.py	100.00% <ø> (ø)
src/felupe/constitution/_models_hyperelasticity.py	100.00% <ø> (ø)
...c/felupe/constitution/_models_linear_elasticity.py	100.00% <ø> (ø)
... and 31 more

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