Adds min-preludes more tests which were seen as slow and their
surrounding neighbours. This drops the file_test runtime on my machine
from about 7s to about 6s.
For a few files that are clearly only testing diagnostics, we drop the
if-present semir ranges and the associated TODO.
All except
`toolchain/check/testdata/interop/cpp/function_param_int*.carbon` and
`toolchain/check/testdata/interop/cpp/function_return.carbon`.
Don't output SemIR for cases that are intended to fail.
Where `--no-dump-sem-ir` is used, change to `--dump-sem-ir-ranges=only`.
Otherwise, add `--dump-sem-ir-ranges=if-present` with a TODO to change
to `only`.
* Split to 4 files: `function_param_int16`, `function_param_int32`,
`function_param_unsupported.carbon`, `function_return`.
* Add // === headlines on group of file shards.
* Rename shard files to shorten them and make them more consistent given
the file context.
* Deduplicate identical .h files and group their tests.
Potential future improvements:
* Split further. For example, pointers and references might be somewhat
separate from int primitives.
* Remove `import_` shard file prefix, as it repeats itself, but leaving
for now as it makes it more explicit.
Part of #5263