Change Bandwidth File format to a more standard/moderm one

Updating the Debian package for tpo/network-health/sbws> I just got the info tag very-long-line-length-in-source-file from lintian, which includes the sentence:

Last but not least, long line in source code could be used to obfuscate the source code and to hide stuff like backdoors or security problems.

It has also been quite difficult to debug issues with these long Bandwidth File lines and create test examples.

Since other teams are also considering changing to other file formats [0], this doesn't look that crazy.

This change would require to change the specification in tpo/core/torspec> and the tools that parse/generate it.