Support full GitHub app authentication (#1986)

* Support full GitHub app authentication
 Refactor GithubIntegration class and add test case for app authentication
Add permissions and repository properties in InstallationAuthorization
Set JWT_EXPIRY=60 by default in GithubIntegration constructor
* Modify existing testcases for GithubIntegration as per the framework and add missing tests
* Provide installation ID for creating the access token instead of getting the first installation
* Add optional permissions support for installation access token
* Add lock around app authentication
* Keep compatibility for importing GithubIntegration from MainClass
* Group app authentication parameters in a class

Co-authored-by: Malik Ammar Akbar <malikammar.akbar@pfizer.com>
Co-authored-by: Enrico Minack <github@enrico.minack.dev>

github/GithubIntegration.pyi

@@ -0,0 +1,34 @@
+from typing import Union, Optional, Dict
+
+from github.Installation import Installation
+from github.InstallationAuthorization import InstallationAuthorization
+from github.PaginatedList import PaginatedList
+from github.Requester import Requester
+
+class GithubIntegration:
+    integration_id: Union[int, str] = ...
+    private_key: str = ...
+    base_url: str = ...
+    jwt_expiry: int = ...
+    jwt_issued_at: int = ...
+    __requester: Requester = ...
+    def __init__(
+        self,
+        integration_id: Union[int, str],
+        private_key: str,
+        base_url: str = ...,
+        jwt_expiry: int = ...,
+        jwt_issued_at: int = ...,
+    ) -> None: ...
+    def _get_installed_app(self, url: str) -> Installation: ...
+    def _get_headers(self) -> Dict[str, str]: ...
+    def create_jwt(self, expiration: int = ...) -> str: ...
+    def get_access_token(
+        self, installation_id: int, permissions: Optional[Dict[str, str]] = ...
+    ) -> InstallationAuthorization: ...
+    def get_app_installation(self, installation_id: int) -> Installation: ...
+    def get_installation(self, owner: str, repo: str) -> Installation: ...
+    def get_installations(self) -> PaginatedList[Installation]: ...
+    def get_org_installation(self, org: str) -> Installation: ...
+    def get_repo_installation(self, owner: str, repo: str) -> Installation: ...
+    def get_user_installation(self, username: str) -> Installation: ...