Add storage extension to save filelog receivers' offsets

[jaehnri]

Fixes #1708

The filestorage extension allows us to keep track of the tail offset for every log file watched by the filelog receivers. This way, whenever an opni-collector-agent pod restarts, they can continue reading the log files from where they stopped.

Previously, whenever a crash or restart happened, agents would read from the start again, sending repeated logs and causing an overflow in the aggregator queues:

2023-09-20T14:18:42.911Z	error	exporterhelper/queued_retry.go:216	Dropping data because sending_queue is full. Try increasing queue_size.	{"kind": "exporter", "data_type": "logs", "name": "otlp", "dropped_items": 100}

Now, on restarts, this is logged to the opni-collector-agents:

2023-09-20T15:42:14.081Z	info	extensions/extensions.go:31	Starting extensions...
2023-09-20T15:42:14.081Z	info	extensions/extensions.go:34	Extension is starting...	{"kind": "extension", "name": "file_storage"}
2023-09-20T15:42:14.082Z	info	extensions/extensions.go:38	Extension started.	{"kind": "extension", "name": "file_storage"}
2023-09-20T15:42:14.083Z	info	adapter/receiver.go:45	Starting stanza receiver	{"kind": "receiver", "name": "filelog/k8s", "data_type": "logs"}
2023-09-20T15:42:14.084Z	info	fileconsumer/file.go:354	Resuming from previously known offset(s). 'start_at' setting is not applicable.	{"kind": "receiver", "name": "filelog/k8s", "data_type": "logs", "component": "fileconsumer"}

Also, I disabled the audit logs by default as rancher-logging does.