Need to add public to RTCIceTransports

[fluffy]

See jsep section 4.1.1.

[alvestrand]

public: Candidates with private IP addresses [RFC1918] will be
filtered out. This prevents exposure of internal network details,
at the cost of requiring relay usage even for intranet calls, if
the NAT does not allow hairpinning as described in [RFC4787],
section 6.

[alvestrand]

Proposal needs to be sent to the list.

Note: Adding the "public" value will mean that creating a PC with this new value will cause an exception when run on old browser (enum compatibility). This is seen as a feature.

[alvestrand]

Related to the IP privacy issue.

[alvestrand]

Changes have been merged. This is now defined in a JSEP reference.