Add Two-sided Arnoldi method #383

Job	Run time
Julia 1 - ubuntu-latest	28m 10s
Julia 1.6 - macOS-latest	29m 10s
Julia 1 - macOS-latest	31m 30s
Julia lts - macOS-latest	30m 2s
Julia 1.6 - windows-latest	32m 18s
Julia lts - windows-latest	28m 20s
Julia lts - ubuntu-latest	25m 4s
Julia 1 - windows-latest	30m 10s
Julia 1.6 - ubuntu-latest	24m 50s
Julia 1 multithreaded - ubuntu-latest	33m 0s
Julia lts multithreaded - ubuntu-latest	28m 59s
	5h 21m 33s

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