Add testsuite for parallel spmv using mutex

[Paramuths]

1. Fix help message for test/runtests.jl
   • clean up nonexistence options
   • add possible options including parallel
2. Create testsuite for parallel spmv using mutex in test/test_parallel.jl

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 10 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/tensors/levels/separate_levels.jl	57.14%	6 Missing ⚠️
src/tensors/levels/mutex_levels.jl	63.63%	4 Missing ⚠️

Files with missing lines	Coverage Δ
src/tensors/levels/mutex_levels.jl	61.14% <63.63%> (+0.24%)	⬆️
src/tensors/levels/separate_levels.jl	76.81% <57.14%> (+8.24%)	⬆️

... and 1 file with indirect coverage changes

[willow-ahrens]

Please undo irrelevant formatting changes, transpose the matrix when necessary, and complete the test suite. Thanks!