PYTHON-4834 Add repr to IndexModel, SearchIndexModel #991

Job	Run time
Build wheels for manylinux_x86_64	2m 19s
Make SDist	40s
Build wheels for manylinux_aarch64	10m 46s
Build wheels for manylinux_ppc64le	10m 22s
Build wheels for manylinux_s390x	10m 51s
Build wheels for manylinux_i686	2m 24s
Build wheels for win_amd6	4m 55s
Build wheels for win32	5m 51s
Build wheels for macos	3m 7s
Download Wheels	10s
	51m 25s

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