[wpiunit] Add Frequency and Measure.inverse()

[WispySparks]

Partially addresses #6683. I'm wondering if it would instead be preferrable to have an inverse() method on Unit that can be overridden by child units. So Velocity and Per would override it instead of having a reciprocal method and Time could override it to give back a frequency. This would then simplify Measure.inverse(). Do you think that's better than the way I've done it now?

[WispySparks]

Yeah I kinda want to not have Frequency be its own type and also use the divide method in inverse since it has dimensional analysis, I'm interested to hear what others think

[bhall-ctre]

and also use the divide method in inverse since it has dimensional analysis

I think there might be missing cases for:

• Measure<Dimensionless>.divide(Measure<Velocity<U>>) where U is not Dimensionless -> Measure<Per<Time, U>>
• Measure<Dimensionless>.divide(Measure<Per<U1, U2>>) where U1 is not Dimensionless -> Measure<Per<U2, U1>>
  • Measure<Dimensionless>.divide(Measure<Per<Time, U>>) -> Measure<Velocity<U>>?
• Measure<Dimensionless>.times(Measure<U>) where U is not Dimensionless -> Measure<U>
  • Currently only the reverse exists (Measure<U>.times(Measure<Dimensionless>))
  • I think there's a couple other instances where the return type of times() is not commutative, but those can be fixed separately

But those should probably be fixed anyways, after which inverse() could just return Value.of(1).divide(meas).

Edit: Opened up a PR to fix these missing cases: https://github.com/wpilibsuite/allwpilib/pull/6696

[PeterJohnson]

Superseded by #6958.