indexmap-rs/indexmap

AI Summary: Implement `insert_sorted_by` and `insert_sorted_by_key` methods for the `IndexMap` data structure. These methods should efficiently insert key-value pairs while maintaining sorted order based on a provided comparison function or key extraction function, respectively. The implementation should leverage existing `binary_search_by` or `binary_search_by_key` for efficient location of the insertion point and then use `insert_before` to perform the insertion.