[SEN-466] new flags for fixed fuzed rate

[GuillaumeDec]

• Use highest two bits of age_gnss in msg_soln_meta to indicate whether or not its value can be used to retrive the time of measurement of the fuzed solution. Useful in the context of pre-alignment, where the latest GNSS solution is forwarded at fuzed rate and timestamped from the IMU samples.
• Use the 5th bit of pos/vel flags to indicate whether the tow is time of measurement (== time of validity) or not. In almost all but the pre-alignment scenario, this is the case, so default value is 0, which also preserves all backward compatibilities.

[reimerix]

LGTM

[denniszollo]

I will review; I think we can reconsider the wording a bit

[GuillaumeDec]

I will review; I think we can reconsider the wording a bit

@denniszollo I'm getting antsy at merging 😅 😉 😁 ...

[denniszollo]

I feel like somewhere we need to describe what "Other" could possible be. I suggest here in the intro paragraph. https://github.com/swift-nav/libsbp/pull/880/files#diff-1669e1e4c34cf7571c33296b08862bedd2a1ce937039283eb73a89b59631fcb7L13

[GuillaumeDec]

Thanks for your feedback Dennis! 🎉 🙏

[denniszollo]

1. Rename "Type of Reported tow" to "tow type"
2. Add exposition about the field at the top of the "navigation" yaml where we orient people about what is going on and what "Time of measurement" means and what "other" means. Time of Measurement means only ONE thing, "other" could be a couple of things.

[GuillaumeDec]

1. Rename "Type of Reported tow" to "tow type"
2. Add exposition about the field at the top of the "navigation" yaml where we orient people about what is going on and what "Time of measurement" means and what "other" means. Time of Measurement means only ONE thing, "other" could be a couple of things.

1. & 2. done ✅

[denniszollo]

LGTM.