Support printing DSO context when symbols aren't avaliable

Currently backtraces don't print enough context when symbols aren't resolved in-process (for whatever reason). If someone wants to attempt symbolising out of process then it may be impossible from the backtrace alone. Quoting @bjorn3: > To be able to actually symbolize the backtraces this would need to print both the path of the DSO (executable or dylib) and the offset within this DSO. It could be a dylib loaded at runtime and thanks to ASLR the exact location of DSOs can't be determined anymore after the fact unless we print it here. > > This could take inspiration on what backtrace-rs does on Fuchsia which unconditionally does backtrace symbolication out of process.