Make sum_inhabited_r not a copy of sum_inhabited_l

See merge request iris/stdpp!288

This existed at least as far back as
iris/stdpp@361308c7, 8 years ago.

rename insert_delete → insert_delete_insert; add new insert_delete matching delete_insert

See merge request iris/stdpp!287

Add a few set and map related lemmas

See merge request iris/stdpp!284

Fix potential stack overflow related to `Pretty N`.

See merge request iris/stdpp!286

add {fst,snd}_map_zip

See merge request iris/stdpp!285

Rewrite cross split lemmas so they can more easily be used for forward reasoning.

See merge request !283

Various setoids lemmas for maps, lists, and option

See merge request iris/stdpp!281

Add lemmas `map_intersection_filter` and `map_difference_filter`.

See merge request iris/stdpp!282

Prove more equivalences for closure operators on relations.

See merge request iris/stdpp!278

As part of this: turn `rtc_nsteps` and `rtc_bsteps` into `↔️`s.

The `_list` lemmas were proposed by @jules and he provided an initial proof specific to `rtc`.

Misc lemmas for maps

See merge request iris/stdpp!280

Misc improvements to `head` and `tail` functions for lists

See merge request iris/stdpp!277