AMReX Particle Reader Adds Time Value Info

This MR adds behavior to the AMReX Particle Reader to read the expected top level Header file where time value information is stored. Previously, no time values were read by the particle reader.

The AMReX Grid Reader reads that header and properly populates the time value for each time step, but the Particle Reader merely checked for the existence of that header and ignored it. Now, it uses that same header reader from the Grid Reader to read that top level header for the time value. It is not expected for that header to be particularly heavy to parse, so this should be a negligible change to the Particle Reader.

Addresses issue paraview/paraview#21612