vpm: init_settings: mkdir_all before set_output_path

[smalltalkman]

os.open_append called by logger.set_output_path calls C._wfopen(wpath, mode.to_wide()) with mode := 'ab'. When the folder $VMODULES\cache does not exist, C._wfopen(wpath, mode.to_wide()) returns NULL and causes an error.

This PR aims to avoid 'V panic: error while opening log file $VMODULES\cache\vpm.log for appending' error.

Before modification:

# echo $VMODULES
/d/gym/test/mingw-w64-packages/mingw-w64-v/vmodules/mingw-w64-i686-v-weekly.2024.19-1

# ll $VMODULES
ls: cannot access '/d/gym/test/mingw-w64-packages/mingw-w64-v/vmodules/mingw-w64-i686-v-weekly.2024.19-1': No such file or directory

# ./v run cmd/tools/vpm/install_test.v
V panic: error while opening log file D:\gym\test\mingw-w64-packages\mingw-w64-v\vmodules\mingw-w64-i686-v-weekly.2024.19-1\cache\vpm.log for appending
v hash: d6d0f9b
print_backtrace_skipping_top_frames is not implemented

[spytheman]

Excellent.