Resolve stack-overflow in Diagonal*Bidiagonal and (Sym)Tridiagonal

[jishnub]

Currently, there are method ambiguities on v1.10, because of which these paths were not being tested. These ambiguities are resolved on the currently nightly, which reveals a stack-overflow in these methods. This arises because an operation like

(D::Diagonal{<:Any, <:LayoutVector}) * (B::Bidiagonal{<:Any, <:LayoutVector})

internally calls

copy(M::Lmul{<:DiagonalLayout,<:BidiagonalLayout})

but this method was calling D * B again, leading to a cycle. To avoid this, we now broadcast D.diag over the other matrix. The added tests all work on nightly where there are no method ambiguities anymore, and the Bidiagonal ones work on current versions as well.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.33%. Comparing base (d315ce3) to head (348f5d8).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #242      +/-   ##
==========================================
- Coverage   90.43%   90.33%   -0.10%     
==========================================
  Files          11       11              
  Lines        1902     1894       -8     
==========================================
- Hits         1720     1711       -9     
- Misses        182      183       +1     

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