PYTHON-4834 Add repr to IndexModel, SearchIndexModel #979

Job	Run time
Make SDist	33s
Build wheels for manylinux_x86_64	2m 16s
Build wheels for manylinux_aarch64	6m 28s
Build wheels for manylinux_ppc64le	6m 28s
Build wheels for manylinux_s390x	6m 27s
Build wheels for manylinux_i686	2m 30s
Build wheels for win_amd6	4m 38s
Build wheels for win32	6m 15s
Build wheels for macos	4m 10s
Download Wheels	1s
	39m 46s

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