Ideas for a v2

Overall, this package has held up well.
If we were to ever consider a v2, here are some changes:

* By default, always treat every variable as addressable, so that comparers and transformers that operate on a pointer can be used.
* Use generics where appropriate:
```go
package cmp
func Comparer[T any](f func(T, T) bool) Option
func FilterValues[T any](f func(T, T) bool) Option
func Transformer[T, R any](name string, f func(T) R) Option
```
```go
package cmpopts
func AcyclicTransformer[T, R any](name string, f func(T) R) Option
func IgnoreFields[T any](names ...string) Option
func IgnoreInterface[T any]() Option
func IgnoreMapEntries[K comparable, V any](f func(K, V) bool) Option
func IgnoreSliceElements[E any](f func(E) bool) Option
func IgnoreType[T any]() Option
func IgnoreUnexported[T any]() Option
func SortMaps[K comparable](f func(K, K) bool) Option
func SortSlices[T any](f func(T, T) bool) Option
```
It's unclear whether `SortMaps` and `SortSlices` should take a less function (i.e., `func(T, T) bool`) or a compare function (i.e., `func(T, T) int`) to match the current `slices.SortFunc` signature.