Copy metrics API from jaeger-lib

[yurishkuro]

Initial round of refactoring. Contains one hack in the form of JLibAdapter needed to keep the factory compatible with the jaeger-client-go. In the follow-up PR we can flip that: copy prom/expvar implementations internally to remove dependency on jaeger-lib from the main code, and keep an adapter to initialize jaeger-client-go.

Partially addresses #3766

[codecov]

Codecov Report

Merging #3767 (4eb9546) into main (dfcded2) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #3767      +/-   ##
==========================================
+ Coverage   97.49%   97.54%   +0.05%     
==========================================
  Files         271      282      +11     
  Lines       16004    16426     +422     
==========================================
+ Hits        15603    16023     +420     
- Misses        317      319       +2     
  Partials       84       84              

Impacted Files	Coverage Δ
cmd/agent/app/builder.go	96.07% <ø> (ø)
cmd/agent/app/configmanager/metrics.go	100.00% <ø> (ø)
cmd/agent/app/httpserver/srv.go	100.00% <ø> (ø)
cmd/agent/app/processors/thrift_processor.go	100.00% <ø> (ø)
cmd/agent/app/reporter/client_metrics.go	100.00% <ø> (ø)
cmd/agent/app/reporter/connect_metrics.go	100.00% <ø> (ø)
cmd/agent/app/reporter/grpc/builder.go	95.16% <ø> (ø)
cmd/agent/app/reporter/grpc/collector_proxy.go	100.00% <ø> (ø)
cmd/agent/app/reporter/metrics.go	100.00% <ø> (ø)
cmd/agent/app/servers/tbuffered_server.go	94.33% <ø> (ø)
... and 58 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update dfcded2...4eb9546. Read the comment docs.