This PR cleans up the `Option` development, upstreaming some results
from mathlib in the process.
Notable changes:
- the name `<op>_eq_some_iff` is preferred over `<op>_eq_some`
- the `simp` normal form for `<$>` is `Option.map`, for `>>=` is
`Option.bind` and for `<|>` is `Option.orElse` (for the former two, this
was already true before this PR). All further lemmas about these
operations are now stated only in terms of
`Option.map`/`Option.bind`/`Option.orElse`. Previously, in some cases
both versions were available, with a prime used to disambiguate (the
primed version was usually the "non-ascii-art" version). Now, there are
no lemmas about the ascii-art versions besides the ones turning them
into the non-ascii-art operations, and there is only one version of
every lemma, about the non-ascii-art operation, and named without a
prime.
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