Small fixes to let BlockTensorMaps work with GPU arrays

[kshyatt]

Need to have ones and zeros use the scalartype and for isomorphism, avoid scalar indexing...

[codecov]

Codecov Report

❌ Patch coverage is 53.84615% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.42%. Comparing base (3392c90) to head (3bfe9c6).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/linalg/factorizations.jl	33.33%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #44      +/-   ##
==========================================
- Coverage   54.66%   54.42%   -0.24%     
==========================================
  Files          17       17              
  Lines        1394     1400       +6     
==========================================
  Hits          762      762              
- Misses        632      638       +6     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.