Improve openPMD diagnostics

[AngelFP]

• Include all components of E and B (i.e., r, t and z) in the openPMD output, even if they are zero. This improves compatibility with post-processing tools such as the openPMD viewer.
• Set the correct units of the B field. Currently no units were set, as the diagnostics still expected the transverse wakefield W instead of E and B.
• In the Tracker, update the tracking time before updating the next object. This makes sure, for example, that the openPMD diagnostics have the correct updated time.
• In the ParticleBunch, use the current global time instead of prop_distance to calculate the z offset. This makes sure that the beam does not jitter in z in the openPMD diagnostics if the beam push and diagnostics do not occur at the same time.

In addition:

• Pass the correct current time of the bunch when pushing it.
• Update tests so that they pass after this fix.