fix: ConnectionOptions conflict between mysql and mysql/promise

[wellwelwel]

@sidorares, this fix is about the .promise() option in issue #1936.

I see that in 3.2.1 release you merged the PR #1949, but in this PR the Connection is changed "globally", however in mysql/promise types it's causing 3 conflicts because it don't needs the promise option, so I rollbacked it before this fix.

---

In this fix:

1. Removed all the PR Add typings for Connection.promise(). #1949 changes (sorry @bluefeet).
2. Removed all the promise options from "global" Connection Interface
3. Imported and added the promise option only in mysql (typings/mysql/index.d.ts)
   • I don't created a new promise method, I just imported the original from:

     import { Pool as PromisePool } from '../../promise';

---

Then:

• ✅ In mysql/promise import, the option promise will not appears
• ✅ In mysql import, both the createConnection and createPool has the promise option and show all the options within them
• ✅ As mentioned by @newtoncodes, in mysql import, the .promise() method returns a Connection instance and not a promise

---

A mysql test example:

// non-promise.ts
import mysql from 'mysql2';

const access: mysql.ConnectionOptions = {
   host: '127.0.0.1',
   user: 'root',
   password: '*',
   port: 3306,
   database: 'mydb',
};

(async () => {
   const db = mysql.createConnection(access).promise();
   
   const [pokemons] = await db.execute('SELECT * FROM pokemons');
   
   await db.end();
   
   console.log(pokemons);
})();

---

A mysql/promise test example:

// promise.ts
import mysql from 'mysql2/promise';

const access: mysql.ConnectionOptions = {
   host: '127.0.0.1',
   user: 'root',
   password: '*',
   port: 3306,
   database: 'mydb',
};

(async () => {
   const db = await mysql.createConnection(access);
   
   const [pokemons] = await db.execute('SELECT * FROM pokemons');
   
   await db.end();
   
   console.log(pokemons);
})();

---

I cloned the latest master after 3.2.1 release and tested it in a real use (locally), it works and build the TypeScript perfectly in both mysql and mysql/promise.

---

Extra tests:

• "skipLibCheck": false,

• "skipLibCheck": true,

• Also, without skipLibCheck.

---

I hope this helps 🙋🏻‍♂️

[wellwelwel]

@sidorares If you don't mind, I'd like to add a CI workflow to test the TypeScript build like an external module without code (just build) after this issue (#1936) is solved. It would prevent any incompatibility between the types before future PRs are approved.

[sidorares]

@sidorares If you don't mind, I'd like to add a CI workflow to test the TypeScript build like an external module without code (just build) after this issue (#1936) is solved. It would prevent any incompatibility between the types before future PRs are approved.

Go for it, I'm very hesitant to merge TS changes exactly because of lack of typing CI