Add state property to BaseConnection to match original mysql package

[HappyZombies]

This PR intends to address #3764 by introducing a state property on the connection object, aligning behavior with the original mysql package.

The new property reflects the current connection status; it only includes the following three states: disconnected, connected, or protocol_error.

The state flow includes:

Default: 'disconnected'

Updated to 'connected' upon successful handshake.

Updated to 'disconnected' after .end() or .close() is called (note that failures can eventually call this method).

Updated to 'protocol_error' on fatal or unexpected protocol errors.

Tests include:

Connects successfully and sets state to connected.

Closes cleanly and sets state to disconnected.

Incorrect credentials result in state protocol_error.

Let me know what you think, and tell me if any changes should be made -- along if we need more tests as well :)

[codecov]

Codecov Report

❌ Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.51%. Comparing base (52bb6e4) to head (bcb70ab).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
lib/base/connection.js	88.88%	1 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@ ## master #3885 +/- ## ========================================== + Coverage 89.78% 90.51% +0.73%  ========================================== Files 86 86 Lines 13607 13614 +7 Branches 1607 1635 +28 ========================================== + Hits 12217 12323 +106  + Misses 1390 1291 -99 

Flag	Coverage Δ
compression-0	89.62% <88.88%> (+0.73%)	⬆️
compression-1	90.49% <88.88%> (+0.73%)	⬆️
static-parser-0	88.09% <88.88%> (+0.73%)	⬆️
static-parser-1	88.85% <88.88%> (+0.73%)	⬆️
tls-0	89.89% <77.77%> (+0.70%)	⬆️
tls-1	90.17% <88.88%> (+0.61%)	⬆️

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[wellwelwel]

A tip would be to use the sleep method instead of setting the setTimeout multiple times with a Promise, for example:

import { sleep } from 'poku'; // ... await sleep(20); // ...

[wellwelwel]

Suggested change

	const raw = connection.connection;
	// use changeUser to induce auth error (assuming user 'nope' doesn't exist)
	let gotErr = null;
	assert.equal(raw.state, "connected");
	raw.on('error', (e) => { gotErr = e; });
	try {
	await connection.changeUser({ user: 'nope', password: 'bad' });
	} catch (err) {
	const raw = connection.connection;
	let gotErr = null;
	assert.equal(raw.state, "connected");
	raw.on('error', (e) => { gotErr = e; });
	try {
	await connection.changeUser({ user: 'NON_EXISTENT_USER', password: 'BAD_PASSWORD' });
	} catch (err) {

[wellwelwel]

Suggested change

	await bad.end();
	await badConnection.end();

[wellwelwel]

Suggested change

	const badConnection = common.createConnection({ password: "WR0NG", user: 'wrong' }).promise();
	const badConnection = common.createConnection({ password: "WR0NG_PASSWORD", user: 'WRONG_USER' }).promise();

[HappyZombies]

I just realized I forgot to add the "authorized" state, so I will be adding that and also fixing the unit tests as per your recommendation :)