tests/test-wireproto.py.out

annotate: build format string separately from annotation data

This prepares for porting to generic templater API.

Note that we cannot use '%*s' to pad white spaces because it doesn't take
into account character widths, as described in 4f5a6df2af92.

Hello, Foobar
['Hello, Fo, =;o', 'Hello, Bar']