refactor(iroh)!: remove dialer::Dialer (#3022)

## Description

Too specific of an API, the uses have been inlined in 
- n0-computer/iroh-gossip#21
- n0-computer/iroh-blobs#34

## Breaking Changes

- removed `iroh::dialer::Dialer` and `iroh::dialer`

## Notes & open questions

<!-- Any notes, remarks or open questions you have to make about the PR.
-->

## Change checklist

- [ ] Self-review.
- [ ] Documentation updates following the [style
guide](https://rust-lang.github.io/rfcs/1574-more-api-documentation-conventions.html#appendix-a-full-conventions-text),
if relevant.
- [ ] Tests if relevant.
- [ ] All breaking changes documented.

Author: dignifiedquire

iroh/src/dialer.rs

@@ -234,7 +234,6 @@
 #![cfg_attr(iroh_docsrs, feature(doc_cfg))]
 
 pub mod defaults;
-pub mod dialer;
 mod disco;
 pub mod discovery;
 pub mod dns;