[Generation] Create configuration path constant and method retriever

We should be able to get config path constant and method if it already exists in the target configuration model.

**Input:**

1. target path information object
2. configuration model object (PhpClass)

**Output:**

Target path and method if it already exists.

**Acceptance Criteria:**

- it should be covered by test case.

**Additional context**

**Mainline branch:** mainline/generate-configuration-model