Use std::optional/string_view

[cyyever]

Summary

This PR changes callers to use std::optional/string_view.

Test plan

Check whether the system can build.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/20213

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❌ 12 Pending, 1 Unclassified Failure

As of commit 9745d37 with merge base 875cc58 ():

UNCLASSIFIED FAILURE - DrCI could not classify the following job because the workflow did not run on the merge base. The failure may be pre-existing on trunk or introduced by this PR:

• periodic / gather-models (gh) (this job did not run on the merge base, so DrCI cannot tell whether the failure is pre-existing)

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[cyyever]

@pytorchbot label "release notes: none"

[rascani]

Thanks for making this change!

Does this remove all uses of torch::executor::optional and executorch::runtime::etensor::optional? If so, then it would probably be good to remove those type aliases to ensure new usages don't get re-introduced.

There are a few clang-format errors coming from lintrunner that need to be cleaned up.