Adds a new type of sharding for drmemtrace analysis tools: by core
instead of by thread.

Introduces a shard_type_t enum (SHARD_BY_THREAD and SHARD_BY_CORE)
passed to a new analysis_tool_t::initialize_shard_type() function to
inform tools of the shard type (this cannot be easily added to the
stream interface as the scheduler is not aware of the shard type).

Adds a new memtrace_stream_t::get_output_cpuid() query to get the
output cpu ordinal, or for replaying as-traced the original traced
cpuid (#6262).  Implements this for the scheduler.

Generalizes analyzer_t to take in scheduler options for SHARD_BY_CORE
to support analysis tools using the full range of schedules.  In this
mode, the core count is the worker count.  Updates the shard index to
be the core ordinal.  Adds time-based scheduling support with
analyzer_t using wall-clock time as the current time.

Adds a number of options to set sharding mode (-core_sharding,
-core_serial (not yet implemented)) and control the schedule
(-sched_quantum, -sched_time, sched_order_time, -record_file,
-replay_file, -cpu_schedule_file).

Updates the basic_counts tool to support core sharding.

Adds a new test core_sharded_test which leverages the analyzer_multi
and option parsing to test the top-level options within a framework
that can capture the output and run multiple tests sequentially in a
simpler framework than having a separate test with an output file for
each parameter being tested.

Left as future work:
+ Convert scheduler_launcher into a new schedule_stats tool
+ Add a new record to indicate STATUS_WAIT
+ Add -core_serial support
+ Convert drcachesim default and -cpu_scheduling to use
  get_output_cpuid()

Issue: #5694

… override

… the docs; clarify next_record time of 0; fix typo; augment comments

…re-oriented