Change initrd 'executable' bool to type enum.

assets/initrd.toml

@@ -11,6 +11,7 @@
 [[files]]
 dest = "vdso.so"
 source = "host/libvdso.so"
+type = "vdso"
 
 [[files]]
 dest = "screenfont.psf"
@@ -19,9 +20,9 @@ source = "../assets/fonts/tamsyn8x16r.psf"
 [[files]]
 dest = "nulldrv1"
 source = "user/nulldrv"
-executable = true
+type = "executable"
 
 [[files]]
 dest = "nulldrv2"
 source = "user/nulldrv"
-executable = true
+type = "executable"