Fix splitting of link header subitems

[redoPop]

This PR fixes the parsing of link header values that contain equals signs:

Before this change:

• Input: "credential=\"foo=\""
• Expected: ["credential", "\"foo=\""]
• Actual: ["credential", "\"foo", "\""]

After this change:

• Input: "credential=\"foo=\""
• Expected: ["credential", "\"foo=\""]
• Actual: ["credential", "\"foo=\""]

[CLAassistant]

All committers have signed the CLA.

[redoPop]

For context: I discovered this bug when it caused Twilio TURN server authentications to fail due to munged credentials, resulting in broken ICE for connections where relay was required. (The browser attempted to use server reflex candidates.)

[redoPop]

@murillo128 Understandable if it's not a priority, but after seeing 1.0.1 go out with a conflicting change I wanted to make sure this wee fix hadn't fallen under the radar! 🙂

[murillo128]

i completely forgot about this, please rebase (if you haven't done so already) and i will merge it

[redoPop]

No prob! Rebase complete! Ran into another tiny bug today but opened a separate PR for that since it's unrelated.

[murillo128]

thank you!