Updated addons api functions and fixed test_project_files.py

[Ramyapatil712]

Purpose

Update addons api functions to fix test_project_files.py tests which were failing after new GV release this year.

Summary of Changes

1. Updated osf_api.py to fix get_user_addon and connect_provider_root_to_node functions
2. Updated settings.py to include new addons api endpoints
3. Updated test_project_files.py to fix the failing tests with new api functions

Reviewer's Actions

git fetch origin pull/287/head:feature/Fix_Project_Files_Tests

Add following items to .env file:
USER_ONE_STAGE1_PAT
USER_ONE_STAGE2_PAT
USER_ONE_STAGE3_PAT
USER_ONE_TEST_PAT

And provide the tokens created for each environment

Note: Create PAT for addon for the user1 on the staging environment and update .env with new token for that environment

Run this test using
tests/test_project_files.py::TestFilesPage -s -v

Testing Changes Moving Forward

Ticket

https://openscience.atlassian.net/browse/ENG-8300