PYTHON-4834 Add repr to IndexModel, SearchIndexModel #975

Job	Run time
Build wheels for manylinux_x86_64	2m 15s
Make SDist	30s
Build wheels for manylinux_aarch64	10m 40s
Build wheels for manylinux_ppc64le	10m 1s
Build wheels for manylinux_s390x	10m 48s
Build wheels for manylinux_i686	2m 21s
Build wheels for win_amd6	5m 3s
Build wheels for win32	5m 10s
Build wheels for macos	3m 37s
Download Wheels	8s
	50m 33s

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