DOCSP-42819: add coding standards workflow

[rustagir]

Pull Request Info

JIRA - https://jira.mongodb.org/browse/DOCSP-42819

Adapted the actions from the source driver repo but changed the rules for when the action should be run and on which filetypes

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[GromNaN]

You need to add a composer.json to install the tools:

    "require": {
        "mongodb/mongodb": "^1.20"
    },
    "require-dev": {
        "doctrine/coding-standard": "^12.0",
        "squizlabs/php_codesniffer": "^3.7",
        "vimeo/psalm": "^5.13"
    }
}

• the phpcs.xml inspired by https://github.com/mongodb/mongo-php-library/blob/master/phpcs.xml.dist
• the psalm.xml inspired by https://github.com/mongodb/mongo-php-library/blob/master/psalm.xml.dist

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[GromNaN]

I've added the phpcs and psalm rules to make the tests pass.