Add support for remote streams

[fancycode]

This allows subscribing streams from any proxy (resolves #548). Using a different proxy for subscribing is based on subscribers country and / or bandwidth limits of publisher proxy.

Note: requires Janus 1.1.0 or newer.

[coveralls]

Pull Request Test Coverage Report for Build 9170665910

Details

• 426 of 2221 (19.18%) changed or added relevant lines in 18 files are covered.
• 15 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+2.1%) to 56.849%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
janus_client.go	0	2	0.0%
grpc_server.go	7	10	70.0%
publisher_stats_counter.go	52	55	94.55%
server/main.go	0	4	0.0%
api_proxy.go	11	37	29.73%
mcu_janus_stream_selection.go	0	59	0.0%
mcu_janus_remote_subscriber.go	0	63	0.0%
mcu_janus_remote_publisher.go	0	89	0.0%
mcu_proxy.go	279	384	72.66%
mcu_janus_client.go	0	126	0.0%

Files with Coverage Reduction	New Missed Lines	%
mcu_proxy.go	1	61.08%
grpc_remote_client.go	2	75.57%
mcu_janus.go	12	0.48%

Totals
Change from base Build 9170643784:	2.1%
Covered Lines:	9471
Relevant Lines:	16660

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💛 - Coveralls