Support for max line length for string and comment

[blueyed]

I've found that luacheck has support for different types of max-line-length:

• New --[no-]max-code-line-length, --[no-]max-string-line-length,
  --[no-]max-comment-line-length CLI options and corresponding
  config and inline options that limit line length only for subsets of lines
  based on line type: string lines have their line endings within a string,
  comment lines have their line endings within a comment, other lines
  are code lines

It would be nice if this was supported by pycodestyle in a similar way:

Given a max line length of 79, you often have to wrap long strings or comments (or append a # noqa comment), which might result in e.g. an error message not being easily greppable.

It would be nice to have e.g. new options max-string-line-length and max-comment-line-length that would be applied for when the line ends with a string or comment, falling back to max-line-length.

[asottile]

Duplicate of #906 (which has ~slightly more context)