Fix part of #4391 : Fix failing build on M1 Macs

Explanation

Some M1 Macs fail to build the Oppia app because of unused imports in some of the proto files in the project. This PR attempts to fix this issue by removing unused imports in proto files. Files affected by this fix are;

• profile.proto
• deprecation.proto

This is a temporary fix and more investigation will need to be done to properly understand why this behavior is erratic and why it only happens in some instances and not in others. More checks are also needed to ensure that proto files only have imports that are used in the proto file before they are merged.

Besides build fixes, this PR also;

• Includes a fix for the buildifier_download.sh which previously did not work for MacOS users.
• Introduces a static_checks.sh file to allow contributors to run all static checks locally before pushing the code to Git.
• Adds a wiki entry in the Static-Analysis-Checks wiki. The entry contains instructions on how to run static checks locally with the static_checks.sh file.

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).