#4917 will expose users of the `Lean` API to the renaming of the hash
map query methods. This PR aims to make the transition easier by adding
deprecated functions with the old names.
The original idea was to use `bif` in computation contexts and `if` in
propositional contexts, but this turned out to be really inconvenient in
practice.
The name `remove` was chosen because it is more popular in mainstream
programming languages, but being consistent with other Lean container
types (including `Lean.HashMap` and `Batteries.HashMap`) is more
important, so let's change the name while we still can.
### Preliminary PRs:
- [x] #4597
- [x] #4599
- [x] #4600
- [x] #4602
- [x] #4603
- [x] #4604
- [x] #4605
- [x] #4607
- [x] #4627
- [x] #4629
### Quick overview over API/naming changes compared to `Lean.HashMap`
and `Batteries.HashMap`:
#### Lean
* `find?` -> `get?`/`getElem?`
* `find!` -> `get!`/`gtetElem!`
* `findD` -> `getD`
* `findEntry?` -> not implemented for now
* `insert'` -> `containsThenInsert` (order reversed in result)
* `insertIfNew` -> `getThenInsertIfNew?` (order reversed in result)
* `numBuckets` -> `Internal.numBuckets`
* `ofListWith` -> not implemented for now
* `Array.groupByKey` -> not implemented for now
* `merge` -> not implemented for now, but you can use `insertMany`
#### Batteries
* `modify` -> not implemented for now
* `mergeWith` -> not implemented for now
* `mergeWithM` -> not implemented for now
