This must have broke at some point during the new `MktPair` and thus
`.fqme: str` updates; mas-o-menos the symbol key in the quote-msg-`dict`
was NOT set to the `MktPair.bs_fqme: str` value and thus wasn't being
processed by the downstream sampling and feed subsys.
So fix that as well as a few other refinements,
- set the `topic: mkt.bs_fqme` in quote msgs obvi.
- drop the "wait for first clearing vlm" quote poll loop; going to fix
the sampler to handle a `first_quote` without a `'last'` key.
- add some typing around calls to `get_mkt_info()`.
- rename `stream_messages()` -> `iter_normed_quotes()`.
411b517d8d