Add extra KV commands: pop, incr, decr, touch - #3

Summary

Added four more commands from Cache API to the CLI: pop, touch, incr, and decr

Commands Added

• touch: updates the expire time for a key in the cache without changing its value
• pop: returns the value for a key and removes the key, optionally also can return expire-time and tag
• incr: increment a key's value by a delta value, by default it's 1.
• decr: similar as incr, but reduces the value, decrementing

Testing

• added 12 new tests validating the implementation including the error and timeout paths.
• converted the pytest fixture cache to generator, so the resource gets closed, earlier it as left open.
• current coverage of tests are 98.29%, meeting the projects spec of 98%+