This adds SemIR structs and implements building `observe` lists, as well
as naming, formatting, and importing `observe` declarations.
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Co-authored-by: Dana Jansens <danakj@orodu.net>
This shifts logic a little so that empty top-level scopes are printed
less often. This affects imports mainly for now, but should be expected
to affect the soon-to-be-added generated scope more significantly.
Assisted-by: Google Antigravity with Gemini 3 Flash
This drops file_test runtime from about 3s to 2.5s on my machine, which
is now ~30% faster than before #5653 slowed things down by adding a lot
of stuff to the production prelude.
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Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
People seemed receptive [on
#toolchain](https://discord.com/channels/655572317891461132/655578254970716160/1379196447827689553),
so proceeding.
For the two name conflicts, I've set it up so that there's a
"foo.carbon" and "foo_with_prelude.carbon", to indicate that the
no-prelude approach is preferred (with a shorter name).
Note min_prelude will require a little more work/thought, I want to
avoid adding `--custom-core` etc.
Richard Smith
Özgür T. ÖnsoyandDana Jansens
Jon Ross-Perkins