BullMQJobQueueStrategy: configurable retries, backoff

[michaelbromley]

Is your feature request related to a problem? Please describe.
Should be possible to configure retry & backoff settings for each job queue. Right now it is set to 0 retries, which is not great for many situations like sending emails.

Describe the solution you'd like
Add a new config option which allows you to configure the settings per job, in the same way that the PollingJobQueueStrategy allows:

vendure/packages/core/src/job-queue/polling-job-queue-strategy.ts

Lines 23 to 29 in a6a4c6f

	export type BackoffStrategy = (queueName: string, attemptsMade: number, job: Job) => number;
	export interface PollingJobQueueStrategyConfig {
	concurrency?: number;
	pollInterval?: number | ((queueName: string) => number);
	backoffStrategy?: BackoffStrategy;
	}

There should be a function which takes the Job instance, and returns a JobsOptions object.

[michaelbromley]

Note: configurable retries can and should also be added to the DefaultJobQueuePlugin.