[monitoring][influxdb] Do not attempt to create database / Allow TCP socket / custom Client

[Steveb-p]

I've created a PR for influxdb-php library introducing ability to write to TCP sockets, for example telegraf's ones - which allows me to write to a local socket instead of directly writing measurements to influxdb. (influxdata/influxdb-php#124)
I'm using a custom version of InfluxDBStorage class (monitoring) because the one from enqueue/monitoring always does try to create a database...

enqueue-dev/pkg/monitoring/InfluxDbStorage.php

Lines 164 to 181 in 0652c5c

	private function getDb(): Database
	{
	if (null === $this->database) {
	if (null === $this->client) {
	$this->client = new Client(
	$this->config['host'],
	$this->config['port'],
	$this->config['user'],
	$this->config['password']
	);
	}
	$this->database = $this->client->selectDB($this->config['db']);
	$this->database->create();
	}
	return $this->database;
	}

...which won't work in above case, because that socket is unable to handle database queries. I'm passing a custom client directly (as constructor $config variable)...

enqueue-dev/pkg/monitoring/InfluxDbStorage.php

Lines 49 to 80 in 0652c5c

	public function __construct($config = 'influxdb:')
	{
	if (false == class_exists(Client::class)) {
	throw new \LogicException('Seems client library is not installed. Please install "influxdb/influxdb-php"');
	}
	if (empty($config)) {
	$config = [];
	} elseif (is_string($config)) {
	$config = $this->parseDsn($config);
	} elseif (is_array($config)) {
	$config = empty($config['dsn']) ? $config : $this->parseDsn($config['dsn']);
	} elseif ($config instanceof Client) {
	$this->client = $config;
	$config = [];
	} else {
	throw new \LogicException('The config must be either an array of options, a DSN string or null');
	}
	$config = array_replace([
	'host' => '127.0.0.1',
	'port' => '8086',
	'user' => '',
	'password' => '',
	'db' => 'enqueue',
	'measurementSentMessages' => 'sent-messages',
	'measurementConsumedMessages' => 'consumed-messages',
	'measurementConsumers' => 'consumers',
	], $config);
	$this->config = $config;
	}

... but it appears that there is no way to pass configuration for measurements writing (since you can either pass a Client instance or config string/array).

I believe there should be a setter for configuration for this case? WDYT? Should using Client or Database instance be configurable as well / instead?

EDIT: For writing I'm replacing

enqueue-dev/pkg/monitoring/InfluxDbStorage.php

Line 112 in 0652c5c

$this->getDb()->writePoints($points, Database::PRECISION_MILLISECONDS);

with

$this->client->write([], $points);

since the currently used in php-enqueue code will call Database's
https://github.com/influxdata/influxdb-php/blob/4a1efb43656a4f2b390201865cfe7051c895dff7/src/InfluxDB/Database.php#L162-L179
eventually anyway with passed Points as payload.