Move all type-hint only imports behind if TYPE_CHECKING

[janosh]

Summary

1ab9e8f ruff enable flake8-type-checking (TCH)
2f54128 move all type-hint only imports behind if TYPE_CHECKING

Related PR: materialsproject/pymatgen#2992

4 main motivations for this change:

1. reduces chance of circular imports
2. can help contributors run tests without installing extra deps like pymatgen.analysis.defects if they were previously in a test's import stack but only used for type hints
3. helps with readability by clearly separating type-only imports
4. can decrease startup time since TYPE_CHECKING=False at run time means some modules won't have to be imported. somewhat negated by the annoyingly long import time of the std lib typing module itself but that has been steadily coming down with newer Python versions.

[codecov]

Codecov Report

Merging #354 (2f54128) into main (7bef4b0) will decrease coverage by 1.33%.
The diff coverage is 19.73%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #354      +/-   ##
==========================================
- Coverage   66.07%   64.74%   -1.33%     
==========================================
  Files          74       74              
  Lines        7101     7157      +56     
  Branches      904      938      +34     
==========================================
- Hits         4692     4634      -58     
- Misses       2140     2224      +84     
- Partials      269      299      +30     

Impacted Files	Coverage Δ
src/atomate2/amset/files.py	0.00% <0.00%> (ø)
src/atomate2/vasp/builders/elastic.py	0.00% <0.00%> (ø)
src/atomate2/vasp/flows/amset.py	0.00% <0.00%> (ø)
src/atomate2/vasp/jobs/amset.py	0.00% <0.00%> (ø)
src/atomate2/common/jobs/defect.py	83.48% <14.28%> (-5.41%)	⬇️
src/atomate2/common/flows/defect.py	82.08% <16.66%> (-7.15%)	⬇️
src/atomate2/vasp/flows/elastic.py	82.05% <16.66%> (-12.55%)	⬇️
src/atomate2/vasp/flows/phonons.py	88.88% <16.66%> (-5.43%)	⬇️
src/atomate2/vasp/jobs/elastic.py	78.31% <16.66%> (-5.64%)	⬇️
src/atomate2/vasp/jobs/phonons.py	80.89% <16.66%> (-5.31%)	⬇️
... and 24 more

[utf]

Great, thank you!