[FEATURE REQUEST] gRPC internal implementation

[LdDl]

Is your feature request related to a problem? Please describe.
Currently gRPC server implementation is outside of this repository (located here: https://github.com/LdDl/license_plate_recognition). It's hard to figure it out how to use gRPC properly (may be no clear enough).

Describe the solution you'd like
Add folder 'server_example' inside of parent folder 'cmd' and add main.go file with simple code example which can be used as boilerplate.

Describe alternatives you've considered
Another repository with boilerplated gRPC server

Additional context
nope

[LdDl]

4fddb6a