fix(handlers): make them executable and remove xargs

handlers/apt/install

@@ -1,2 +1,2 @@
 #!/bin/sh
-xargs sudo apt install "$@"
+sudo apt install "$@"

handlers/apt/ppa

@@ -1,2 +1,2 @@
 #!/bin/sh
-xargs add-apt-repository "$@"
+add-apt-repository "$@"

handlers/arch/install

@@ -1,2 +1,2 @@
 #!/bin/sh
-xargs sudo pacman -S --needed --noconfirm "$@"
+sudo pacman -S --needed --noconfirm "$@"