feat(profile): set / unset handle

[maurerbot]

One approach for a v0 is to use a url shortner (<short domain>/<handle>) with some proxy rules to my.rollup.id.

This v0 version can simply be handles registered on a first come first basis to a KV by setting "primary" address in connected accounts.

We can then follow up with governance as described here: #1452

[maurerbot]

If handles are stored in KV should they be the Key to the profile data or key to the account sub?