Break JobId=... out from this, and only print the StepId=... bit.
This allows us to use %pJ in several additional places, and follows
the newer formatting used elsewhere of JobId=... StepId=... .

Due to how this code works, the end result is admittedly a bit uglier,
but the end result as printed to the logs is preferrable.

Add xasserts() to crash development builds if the wrong struct
is fed in, and fall back to checking the field and returning 'CORRUPT'
if the magic value is not found for production builds rather than
print garbage (and risk an out-of-bounds memory access).

Set when step is created, xassert() when the step is being destroyed.

Give the xassert a chance to fail instead of an invalid memory
access. Also help avoid issues with new logging code if the wrong
struct was passed in.

Need to set found_other_formats to still consume the %.0s if not other
format strings are included.

Use the embedded pointer back to the job_record struct to print that
followed by the step_id value.

Also switch to __func__ and plugin_type where applicable.

Further work to convert StepId structures will be handled later.

Do this instead of looking the job_id back up immediately.

Convert this to %pJ while here, and fix incorrect comments for
srun_allocate_abort().

Rather than pulling the job_id out of job_ptr just to have it call
find_job_record() to find it again, just cut out the indirection.

Switch a few fatal() log messages to fatal_abort() where appropriate.

Permits use of %pJ. Convert the upstream calling location _preempt_jobs()
to %pJ while changing its signature as well.

Switch to plugin_type and __func__ while converting in select_serial.c.

Allows for %pJ conversion.

Allows conversion to use %pJ to print in canonical format, although
some care is needed here to avoid introducing a circular dependency
between structs from slurmctld.h and job_resources.h.

No longer print out the job name field in debug messages as well.

Change to __func__ in messages while editing them.

Standardize on "JobId=..." where the job_ptr is not available.

Change function signature for _write_nid_file to use the job_ptr instead.

Convert any changed log messages to __func__ while here as well,
and standardize on "JobId=" for locations that cannot use %pJ.

Slurm has used used both "JobID" and "JobId", but treat the latter as the
canonical format given the long-standing use in slurm_sprint_job_info(),
and several user-visible locations in scontrol.

This seems fairly verbose.  We can change it back if/when needed.