proposal: x/net: net/http: Export function to parse http comma separated list header

[shaj13]

What did you expect to see?

Essentially, I'd like golang.org/x/net or net/http to expose functions to parse an HTTP comma-separated list header.
e.g Cache-Control and WWW-Authenticate

Note:
Content-Type and Content-Disposition can be parsed using mime

Currently, most of the go developers use alternatives like the archived gddo/httputil/header/.

net/http already expose ParseTime that exist in gddo/httputil/header/.

So I'd like to copy the underlying gddo/httputil/header/ implementation into x/net/http/httpguts
and change the method signatures to be as net/http ParseTime.

// ParseList parses a comma separated list of values. Commas are ignored in
// quoted strings. Quoted values are not unescaped or unquoted. Whitespace is
// trimmed.
func ParseList(header string) []string {}

// ParsePairs extracts key/value pairs from a comma-separated list of
// values as described by RFC 2068 and returns a map[key]value
func ParsePairs(header string) map[string]string {}

Example:
https://play.golang.org/p/LrsYjRqUJzP

[ianlancetaylor]

CC @neild @bradfitz

[seankhliao]

#41046 would be a more general solution, and maybe it should be moved off hold now that it's an RFC?