Chip field in manifest metadata unused when building flash loader

[tmplt]

I'm refactoring some common functionality from cargo-flash into probe-rs-cli-util and noticed that the package.metadata.chip from the firmware manifest is only written to METADATA if found. When building the flash loader, only --chip is used.

Below displays the full scope-usage of chip:

https://github.com/probe-rs/cargo-flash/blob/0615fd5519c80cd1a7379745230798765978f1fa/src/main.rs#L360-L367

And when the flash loader is built:

https://github.com/probe-rs/cargo-flash/blob/0615fd5519c80cd1a7379745230798765978f1fa/src/main.rs#L414-L426

I presume this is a regression from #31?

[tmplt]

When #188 merges this issue moves upstream to probe-rs-cli-util::common_options.

[Yatekii]

@Tiwalun what do you think, should we implement this in probe-rs-cli-util or just in cargo-flash?