Add torch_geometric.utils.lexsort

[ebrahimpichka]

resolves #7743
Added Pytorch implementation of numpy lexsort.

[codecov]

Codecov Report

Merging #7775 (bb687ba) into master (a90949d) will increase coverage by 0.04%.
The diff coverage is 87.50%.

❗ Current head bb687ba differs from pull request most recent head 33b291b. Consider uploading reports for the commit 33b291b to get more accurate results

@@            Coverage Diff             @@
##           master    #7775      +/-   ##
==========================================
+ Coverage   91.56%   91.60%   +0.04%     
==========================================
  Files         452      453       +1     
  Lines       25547    25541       -6     
==========================================
+ Hits        23392    23397       +5     
+ Misses       2155     2144      -11     

Impacted Files	Coverage Δ
torch_geometric/utils/lexsort.py	81.25% <81.25%> (ø)
...h_geometric/contrib/explain/graphmask_explainer.py	90.34% <100.00%> (+4.27%)	⬆️
torch_geometric/nn/models/dimenet.py	99.67% <100.00%> (ø)
torch_geometric/sampler/utils.py	93.44% <100.00%> (-0.21%)	⬇️
torch_geometric/utils/__init__.py	100.00% <100.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more