add `LinSolverDirectLUSOL`, with initial support for solving Ax = rhs

[superwhiskers]

• adds a function for expanding symmetric matrices only stored as their half
• adds a function for extracting coordinates of nonzeroes from matrices
• documents a deficiency in the Csc class
• modifies the build system to compile fortran code used in LUSOL
• fixes some additional issues made in using index_type/real_type pervasively
• adds a method to the logger class to extract the log level
• adds tests on symmetric matrix expansion

[pelesh]

• documents a deficiency in the Csc class

@superwhiskers, please create a separate issue rather than adding comments to the code.

[pelesh]

It seems that changes to CMake caused GPU builds to break. An example error message looks like:

[ 34%] Building CXX object resolve/matrix/CMakeFiles/resolve_matrix.dir/MatrixHandlerHip.cpp.o
/ccs/home/peles/src/resolve/resolve/resolve/matrix/MatrixHandlerHip.cpp:58:18: error: no matching function for call to 'rocsparse_dcsrmv_analysis'
        status = rocsparse_dcsrmv_analysis(handle_rocsparse,
                 ^~~~~~~~~~~~~~~~~~~~~~~~~
/opt/rocm-5.6.0/include/rocsparse/rocsparse-functions.h:3387:18: note: candidate function not viable: no known conversion from 'index_type *' (aka 'long *') to 'const rocsparse_int *' (aka 'const int *') for 8th argument
rocsparse_status rocsparse_dcsrmv_analysis(rocsparse_handle          handle,

I'll investigate more.

[pelesh]

@superwhiskers, I tested this branch and everything looks good. I fixed a couple of minor build warnings in PR #156. I will merge this PR after #156 is merged.

[superwhiskers]

156 is merged.