Only KEX packets are allowed during KEX.
First packet must be kexinit when strict-kex
is negotiated

Includes updating some embassy versions, takepipe needed restructuring
to use split(). Takepipe isn't tested yet

Required updating embedded-io-async too

Also update to latest cyw firmware

Some picow menu improvements

Bump embassy version, embassy-net-tuntap is now its own crate
Also fix some warnings

Fix path for "size" of target in ci

Add sshwire::ssh_write_vec() helper

Wasn't being saved to flash before

Untested

A few other bits of tidying too

Also various extra tracing

Moved cyw43 git revision to top level Cargo.toml

embassy demos go back into the workspace, seems to work OK for the time
being.

Added toplevel Cargo.lock

Fixes embassy/demos/common CI

update other deps

Instead we set a flag in MethodPubkey which is the only use case for it.

Split verify() into ed25519 and rsa specific functions

This fixes PuTTY connecting. Also improve error printing

- uart is available as a "serial1" feature.
- updated to newer embassy and cyw43 with bind_interrupts
- moved picowmenu flag handlers into a separate method

Better echo handling
auth_password and auth_pubkey server behaviour methods are now async

Need to figure out echo problem