Add sparse matrix interface (#349) #2020

Job	Run time
Examples Conda Py3	1m 52s
Pytest Conda Py3 POCL	3m 6s
basedpyright	2m 33s
Pytest Conda Py3 Intel	2m 53s
Tests for downstream project meshmode	11m 9s
Tests for downstream project grudge	12m 11s
Tests for downstream project mirgecom_examples	5s
Documentation	2m 38s
Ruff	11s
Typos	6s
Tests for downstream project mirgecom	7s
	36m 51s

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