[debuginfo-tests][Dexter] Fix some Windows-unfriendly Dexter behaviours
These are some minor things that I've run into on Windows, largely in
error handling paths:
* Giving --lldb-executable on Windows triggers a "useless option" code
path, which touches an attribute that only exists in the
list_debuggers tool. Switch this to use hasattr, which will work in
all subtools.
* We were over-decoding some text reporting errors, but only in an
exception path
* The path to lldb on Windows needs to be quoted (even though dexter
isn't making use of it).
Differential Revision: https://reviews.llvm.org/D74546
GitOrigin-RevId: 5ee4a03bc916d2925b9431c53b7da0d3ce7e2b9e
3 files changed
