feat: add conn-level infileStreamFactory option

[loozhengyuan]

This PR provides support for the infileStreamFactory option at the connection level. This will be useful for users who are looking to validate the file path at the connection/pool level. For downstream libraries like sequelize and typeorm, exposing this option at the connection-level will also allow users to set infileStreamFactory option through the dialectOptions and extra parameters respectively.

With the change, the infileStreamFactory option can be supplied when instantiating a new connection:

const fs = require("fs");
const mysql = require('mysql2');

const connection = mysql.createConnection({
  user: 'test',
  database: 'test',
  infileStreamFactory: (path) => {
    // Validate file path
    const validPaths = ['/tmp/data.csv'];
    if (!validPaths.includes(path)) {
      throw new Error(`invalid file path: ${path}: expected to be one of ${validPaths.join(',')}`);
    }
    return fs.createReadStream(path);
  }
});

connection.query('LOAD DATA LOCAL INFILE "/tmp/data.csv" INTO TABLE test', onInserted);

Fixes #2151

[sidorares]

lgtm!

[sidorares]

@loozhengyuan published as v3.6.0