backtracegenerator: cache raw debugger output and give the user access to it
this now means we capture both stdout and stderr. shouldn't be a huge problem because we ultimately run the output through the gdb parser anyway and that filters out most of the noise. plus, we mostly care about the traces in sentry anyway and those are generated by the preamble and clean.
there are two ways to get the data
- the inlinemessage now sports a details button that opens a txt file
- via the developer view, which no longer shows a useless error
there area also now verbosity lines to mark the beginning and the end of the debugging session