Add instruction encoding entries to drmemtrace

Today, the drmemtrace format does not include instruction encodings or even opcodes beyond identifying branch types. This is sufficient for functional cache simulation, as in drcachesim, but for core simulation the operand dependencies and ideally the opcodes are needed. The solution today is to preserve the application binaries for the executable and libraries, with support for mapping them in during trace analysis in order to decode the instructions (using the same support built for post-processing offline traces). Adding the encodings into the trace proper would make the trace self-contained. It is also the simplest solution for supporting dynamically-generated code that has no binary to query later: https://github.com/DynamoRIO/dynamorio/issues/2062#issuecomment-985707479