Add a CI that fails if line length exceeds 79

[harendra-kumar]

We can run something like this on all .hs files:

awk '{if (length($0) > 79) {print "Line length exceeds 79: " length($0); print $0; exit 1;}}'

We can add this in the hlint CI itself. If some files have too many issues to fix we can add it to hlintignore file. Ideally we should fix line lengths in at least those files that are hlint free so that we do not end up adding those files to the hlintignore.