Pretty printer for #trace_entry_t-format traces

Traces on disk are a sequence of 12 byte entries of type #trace_entry_t.
Currently we visualize such traces in binary form as described here: https://dynamorio.org/page_debug_memtrace.html#autotoc_md136.

We want to implement a tool similar to `view` (in `clients/drcachesim/tools/view.cpp`) to "pretty print" on-disk-format-traces.
The reason we cannot use the `view` tool is that it operates on a higher level representation of traces (#memref_t described here: https://dynamorio.org/sec_drcachesim_format.html) and not #trace_entry_t.

Since tools can operate on both #memref_t and #trace_entry_t representation of traces (https://dynamorio.org/sec_drcachesim_newtool.html), we believe a visualization tool for #trace_entry_t traces will be helpful for developers working on tools that manipulate #trace_entry_t.