Switch to running the actual install_gadget.py

This re-uses the OutputView code to run the installer script. Refactor
to remove connection from the base OutputView (and other places, it
wasn't used - only used after ConnectionUp).

This also consolidates the stdout and stderr buffers for running jobs.
The distinction was always arbitrary and probably an error, based on the
fact that they were separate in the APIs not based on usability.

install_gadget.py

@@ -163,6 +163,7 @@ for custom_file_name in functools.reduce( operator.add,
 
 
 failed = []
+succeeded = []
 all_adapters = installer.ReadAdapters(
   read_existing = args.update_gadget_config )
 
@@ -179,12 +180,13 @@ for name, gadget in gadgets.GADGETS.items():
 
   installer.InstallGagdet( name,
                            gadget,
+                           succeeded,
                            failed,
                            all_adapters )
 
 
 for name, gadget in CUSTOM_GADGETS.items():
-  installer.InstallGagdet( name, gadget, failed, all_adapters )
+  installer.InstallGagdet( name, gadget, succeeded, failed, all_adapters )
 
 if args.no_gadget_config:
   print( "" )
@@ -193,12 +195,15 @@ if args.no_gadget_config:
 else:
   installer.WriteAdapters( all_adapters )
 
-if failed:
-  raise RuntimeError( 'Failed to install gadgets: {}'.format(
-    ','.join( failed ) ) )
-
 if args.basedir:
   print( "" )
   print( "***NOTE***: You set --basedir to " + args.basedir +
          ". Therefore you _must_ ensure this is in your vimrc:\n"
          "let g:vimspector_base_dir='" + vimspector_base + "'" )
+
+if succeeded:
+  print( "The following adapters were installed successfully: {}".format(
+    ','.join( succeeded ) ) )
+
+if failed:
+  sys.exit( 'Failed to install adapters: {}'.format( ','.join( failed ) ) )