Introduce Global Constants

[danehans]

Some values are being repeated throughout the codebase. Take the EPP gRPC listening port for example:

$ grep -ri 9002 pkg/
pkg/ext-proc/test/benchmark/benchmark.go:	svrAddr       = flag.String("server_address", "localhost:9002", "Address of the ext proc server")
pkg/ext-proc/test/benchmark/benchmark.go:	port = 9002
pkg/ext-proc/test/hermetic_test.go:	port = 9002
pkg/ext-proc/main.go:		9002,

We should audit CLI flag usage and create public constants for values that are used repeatedly in the codebase.

[adarshagrawal38]

/assign

[adarshagrawal38]

Hi @danehans
I am thinking of using DefaultGrpcPort constant defined in pkg/ext-proc/server/runserver.go in benchmark.go to remove repetition of 9002.

And how do I look for other repeated values?