Add `measure` field to the PIREP values

[nabeelio]

Add a measure field where it would be "fuel", "mass", "length", and the expectation is that only the "native" units are populated so they're converted properly.

Maybe measure is not the best name.

[FatihKoz]

While adding that field, please also fix/check the manual pirep entry -> block fuel value recorded to database without being converted to phpvms defaults.

[exciler]

@nabeelio Be aware that I just fixed the addition of @FatihKoz to #1040. I´m not sure what else should be done in #1040 regarding the "measure" field.

[nabeelio]

Yea that should have been a separate issue but it's ok