[OPIK-318] - [Prompt library] SDK Prompt implementation - create/get

[japdubengsub]

Details

Basic implementation of the create() and get() API methods.
Added a class named Prompt for manual initialization.
You can use:

import opik

client = opik.Opik()
prompt = client.create_prompt(name="classification", prompt="some template")

or

from opik import Prompt
prompt = Prompt(name="classification", prompt="some template")

Testing

e2e tests are added