Fix provider option handling in Olive commands

[devang-ml]

Describe your changes

Fix provider option handling. Use fp32 as default target precision in auto-opt command.

Checklist before requesting a review

• [ ] Add unit tests for this change.
• [ ] Make sure all tests can pass.
• [ ] Update documents if necessary.
• [ ] Lint and apply fixes to your code by running lintrunner -a
• [ ] Is this a user-facing change? If yes, give a description of this change to be included in the release notes.
• [ ] Is this PR including examples changes? If yes, please remember to update example documentation in a follow-up PR.

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