Added line numbers to the debug output of PDL bytecode.

This is a small diff that splits out the debug output for PDL bytecode. When running bytecode with debug output on, it is useful to know the line numbers where the PDLIntepr operations are performed. Usually, these are in a single MLIR file, so it's sufficient to print out the line number rather than the entire location (which tends to be quite verbose). This debug output is gated by `LLVM_DEBUG` rather than `#ifndef NDEBUG` to make it easier to test.

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D114061