Go mod has too many dependencies

[bill3tt]

Mimic currently has one Go mod file at the top level of the repo. This file contains all of the dependencies needed for all examples in addition to the main Mimic code.

We should avoid imposing these dependencies on developers by splitting out the main mimic code and examples into separate subdirectories with separate go mod files.

For example:

├── examples
│   └── go.mod
└── mimic
    └── go.mod