Add tutorial with manual sparsity pattern #499

Job	Run time
Julia 1.6 - ubuntu-latest - x64 - pull_request	33m 17s
Julia 1.6 - macOS-latest - x64 - pull_request	36m 56s
Julia 1.6 - windows-latest - x64 - pull_request	40m 56s
Julia 1 - ubuntu-latest - x64 - pull_request	32m 59s
Julia 1 - macOS-latest - x64 - pull_request	47m 46s
Julia 1 - windows-latest - x64 - pull_request	34m 45s
Julia nightly - ubuntu-latest - x64 - pull_request	5m 21s
Julia nightly - macOS-latest - x64 - pull_request	9m 31s
Julia nightly - windows-latest - x64 - pull_request	6m 48s
	4h 8m 19s

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