Fix #4622: Android Wiki migration

[gp201]

Explanation

• Fixes Migrate Android wiki to store source files in oppia-android repository #4622
• The PR does the following: This PR moves the android wiki into the oppia-andoird codebase allowing contributors to make PRs to the wiki along with changes to the codebase itself. This PR also introduces a GitHub Action (Runs when a PR is merged into develop and when a user makes change to the wiki via the web interface) that copies the content of the wiki folder along with the git history of the wiki folder and deploys it to the oppia-android wiki repository.

The steps followed to achieve this wiki migration are present here: Oppia Android Wiki Migration V2.pdf

Note: Please ensure GitHub actions have write permissions. Please follow these instructions to enable it:

GrantingReadandWritePermissionsonGitHub_PDF.pdf

Essential Checklist

• The PR title and explanation each start with "Fix #bugnum: " (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• Any changes to scripts/assets files have their rationale included in the PR explanation.
• The PR follows the style guide.
• The PR does not contain any unnecessary code changes from Android Studio (reference).
• The PR is made from a branch that's not called "develop" and is up-to-date with "develop".
• The PR is assigned to the appropriate reviewers (reference).

For UI-specific PRs only

If your PR includes UI-related changes, then:

• Add screenshots for portrait/landscape for both a tablet & phone of the before & after UI changes
• For the screenshots above, include both English and pseudo-localized (RTL) screenshots (see RTL guide)
• Add a video showing the full UX flow with a screen reader enabled (see accessibility guide)
• Add a screenshot demonstrating that you ran affected Espresso tests locally & that they're passing