PYTHON-4834 Add repr to IndexModel, SearchIndexModel #996

Job	Run time
Make SDist	38s
Build wheels for manylinux_x86_64	2m 19s
Build wheels for manylinux_aarch64	10m 40s
Build wheels for manylinux_ppc64le	9m 50s
Build wheels for manylinux_s390x	10m 27s
Build wheels for manylinux_i686	2m 19s
Build wheels for win_amd6	5m 18s
Build wheels for win32	5m 20s
Build wheels for macos	2m 33s
Download Wheels	7s
	49m 31s

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