Support Gaussian charge model for int1e_grids #925

Job	Run time
macos-build (3.7)	1h 13m 16s
macos-build (3.7)	1h 13m 16s
linux-build-aarch64 (ubuntu-20.04, cp37-cp37m)	10m 47s
linux-build-aarch64 (ubuntu-20.04, cp37-cp37m)	10m 47s
linux-build (ubuntu-20.04, 3.7)	1h 4m 12s
linux-build (ubuntu-20.04, 3.7)	1h 4m 12s
linux-build-aarch64 (ubuntu-20.04, cp38-cp38)	8m 50s
linux-build-aarch64 (ubuntu-20.04, cp38-cp38)	8m 50s
linux-build (ubuntu-20.04, 3.8)	1h 3m 50s
linux-build (ubuntu-20.04, 3.8)	1h 16m 47s
linux-build-aarch64 (ubuntu-20.04, cp39-cp39)	9m 20s
linux-build-aarch64 (ubuntu-20.04, cp39-cp39)	9m 20s
linux-build (ubuntu-20.04, 3.9)	1h 12m 57s
linux-build (ubuntu-20.04, 3.9)	1h 12m 57s
linux-build (ubuntu-20.04, 3.10)	1h 15m 8s
linux-build (ubuntu-20.04, 3.10)	1h 15m 8s
linux-build (ubuntu-20.04, 3.11)	1h 3m 41s
linux-build (ubuntu-20.04, 3.11)	1h 3m 41s
	14h 56m 59s

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