Add corresponding operate_to! method for Matrix-scalar product

[blegat]

Needed for JuliaAlgebra/StarAlgebras.jl#21

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 91.75%. Comparing base (69b1c51) to head (7f10e04).
Report is 3 commits behind head on master.

❗ Current head 7f10e04 differs from pull request most recent head 7c5ce30. Consider uploading reports for the commit 7c5ce30 to get more accurate results

Files	Patch %	Lines
src/implementations/LinearAlgebra.jl	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #273      +/-   ##
==========================================
- Coverage   91.92%   91.75%   -0.17%     
==========================================
  Files          23       23              
  Lines        2216     2220       +4     
==========================================
  Hits         2037     2037              
- Misses        179      183       +4     

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[blegat]

Ready for review, I'll merge in a few days if there is no objection