FIX #10274: Create global initial version constant and use it for initializing all the versioned entities

[Patrick-Haselof]

Overview

1. This PR fixes or fixes part of Create global initial version constant and use it for initializing all the versioned entities #10274.
2. This PR does the following: This PR does the following: According to the Issue "Currently, the initial value for the version number is hardcoded in the domain layer for all the entities which make it open for any entity to add incorrect initial version number", following by suggesting the creation of a Global Variable to act as a consultable constant that all files that require the initial version number can access. It was also pointed that there may be more files that needed refactoring, so after doing what was suggested and created a constant called INITIAL_ENTITY_VERSION in feconf.py, I tried to find more files that needed to be modified. The files controllers and domain have been fully searched:

Modified files:

• exp_domain.py
• topic_domain.py
• collection_domain.py
• exp_fetchers_test.py
• question_domain.py
• story_domain.py
• subtopic_page_domain.py

Found that needed refactoring but needs to be looked into/Uncertain of how to properly modify:

• skill_domain.py
• stats_domain.py

This Issue fix is pure refactoring and no logic has been modified or added

Essential Checklist

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• I have linked the issue that this PR fixes in the "Development" section of the sidebar.
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Proof that changes are correct

This is a simple refactoring work. The logic has not been altered and avoided parts of the code that I did not understand or was reluctant to refactor(such files are listed in the PR description). Ran the according test file for each refactored file and the local server is working.

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[oppiabot]

Hi @Patrick-Haselof, PRs made from develop branch are not allowed. Also PRs made from develop branch or from a branch whose name is prefixed with develop, release or test are not allowed. So this PR is being closed. Please make your changes in another branch and send in the PR. To learn more about contributing to Oppia, take a look at our wiki (Rule 1 specifically). Thanks!

[oppiabot]

Assigning @lkbhitesh07 for the first pass review of this PR. Thanks!

[github-actions]

Hi! @Patrick-Haselof Welcome to Oppia! Could you please follow the instructions here and sign the CLA Sheet to get started? You'll need to do this before we can accept your PR. Thanks!