Rename Events<E>.send() to Events<E>.write()

## Bevy version
0.16.0
## Issue
We obsoleted send() method from EventWriter in favor of write(), why shouldn't we obsolete Events<E> send() method as well (and add write() and write_batch() methods for the sake of consistency?)
https://docs.rs/bevy/latest/bevy/prelude/struct.Events.html#method.send
https://docs.rs/bevy/latest/bevy/prelude/struct.EventWriter.html#method.write