private `numpy.lib` annotations to help reduce the squiggly in `numpy/lib/*.py`

[jorenham]

• lib._utils_impl._median_nancheck - squiggly @ numpy/lib/_function_base_impl.py:4074
• lib._stride_tricks_impl._broadcast_shape - squiggly @ numpy/lib/_function_base_impl.py:2259
• lib._histograms_impl._get_bin_edges()- squiggly @ numpy/lib/_histograms_impl.py:{858, 861}
• lib._function_base_impl._QuantileMethods - squiggly @ numpy/lib/_function_base_impl.py:4828
• lib._function_base_impl.vectorize (_in_and_out_core_dims and _get_ufunc_and_otypes) - squiggly @ numpy/lib/_function_base_impl.py:{2623, 2634}

These should be ported to numpy as well (but we start here to ensure stubtest likes it)