git pre-commit hooks + basic config

Summary

Add basic pre-commit hooks to the repo. To catch, for example, broken symlinks (https://github.com/WorldHealthOrganization/app/pull/1670) Link: https://github.com/pre-commit/pre-commit-hooks

Possible config file. Should be run against every file in the existing tree to see what issues might come up.

# .pre-commit-config.yaml
-   repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v3.3.0  # Use the ref you want to point at
    hooks:
    -   id: trailing-whitespace
    -   id: check-added-large-files
    -   id: check-case-conflict
    -   id: check-executables-have-shebangs
    -   id: check-json
    -   id: check-symlinks
    -   id: detect-private-key
    -   id: end-of-file-fixer

Checklist:

• Searched the existing issues to ensure you are not creating a duplicate.
• Followed the Contributor Guidelines.