Run with debug_assertions enable and less optimization test builds

[George-Ogden]

Summary

Compile tests with debug_assertions and without optimizations set to level 3.
Fixes #341

Changes

• only remove debug assertions when compiling non-debug builds
• only optimize when compiling non-debug builds
• run tests with debug builds
• use an enum to represent the cargo subcommand

Testing

Please help with this. I'm not sure of the best way to test this.

• cargo oxide run <example> passes
• cargo test --workspace passes
• New example added (if applicable)

Checklist

• All commits signed off (git commit -s)
• SPDX headers on new source files (no new source files)

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