Standardize node matching APIs (#3327)

* add lowest mode and universal flag to `Editor.nodes`

* add `mode` handling to all transforms

* add extra `Editor.is*` helpers

* change `Editor.previous` to make all optional

* change `Editor.next` to make all optional

* change `Editor.match` to make all optional

* add `Editor.void` helper

* remove non-function match arguments

* remove NodeMatch interface

* change to lowest match by default everywhere

* rename `Editor.match` to `Editor.above`

* use new helpers

* cleanup

* make NodeEntry generic, cleanup

* fix NodeEntry generics

* ensure only ancestors are returned from Editor.above

* add type-narrowing to `Editor.nodes`, remove extras

* remove other Node entry types

* cleanup

* remove `Editor.block` and `Editor.inline` helpers