Support secure gRPC channel between agent and collector

[yurishkuro]

Extends PR #1311 (which was in ghouscht:master, hard to add to directly)

[codecov]

Codecov Report

Merging #1391 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #1391   +/-   ##
======================================
  Coverage     100%    100%           
======================================
  Files         164     164           
  Lines        7460    7488   +28     
======================================
+ Hits         7460    7488   +28

Impacted Files	Coverage Δ
cmd/collector/app/builder/builder_flags.go	100% <100%> (ø)	⬆️
cmd/agent/app/reporter/grpc/collector_proxy.go	100% <100%> (ø)	⬆️
cmd/agent/app/reporter/grpc/flags.go	100% <100%> (ø)	⬆️

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[tiffon]

:stamp:

[yossishm]

Hi,
A Q?
On which Jaeger Collector/Agent version is this issue resolved? (I use latest - 1.11)

I configured a tls on p 14250 between Agent and Collector and Using a wireshark container sniffing I can see the spans which means they aren't encrypted (Did the same TLS checkup on Collector to elastic and data was encrypted).

Attaching sniffing snapshot.

Thanks,
Y