Add arg tol for dense to block unitensor conversion

[j9263178]

https://github.com/Cytnx-dev/Cytnx/issues/388

[codecov[bot]]

Codecov Report

Attention: 10 lines in your changes are missing coverage. Please review.

Comparison is base (c93b318) 17.81% compared to head (cb9f24e) 17.81%.

Files	Patch %	Lines
src/BlockUniTensor.cpp	0.00%	4 Missing :warning:
include/UniTensor.hpp	0.00%	3 Missing :warning:
src/UniTensor_base.cpp	0.00%	3 Missing :warning:

Additional details and impacted files

@@              Coverage Diff               @@
##           dev-master     #400      +/-   ##
==============================================
- Coverage       17.81%   17.81%   -0.01%     
==============================================
  Files             220      220              
  Lines           48761    48765       +4     
  Branches        19955    19955              
==============================================
  Hits             8686     8686              
- Misses          35871    35875       +4     
  Partials         4204     4204              

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.