Prepend install prefix /bin to PATH

As .buildconfig key run-opts is not currently usable one needs to create "Command" to run the program with the wanted arguments.

However, "Command" has one caveat when using "host system" for the build; the command for being run is expected to be found from PATH thus one needs to specify working directory or relative/absolute path to the binary in the installation prefix (i.e. /home/<user>/.cache/gnome-builder/install/<project-name>/host).

This PR removes the need to play with the paths to the installation prefix.

Merge request reports