feature: add victoria-logs-k8s-stack chart

[hagen1778]

I'd like to have a k8s chart that would help me to collect the logs from services&applications that run in k8s clusters. Similarly to https://github.com/VictoriaMetrics/helm-charts/tree/master/charts/victoria-metrics-k8s-stack I want it to be all-in-one solution for logs, including the following components:

• victoria-logs server for storing and serving logs. Should be adjustable with number of replicas, where each replica stores the complete copy of the data
• logs-collectors for receiving or pulling logs from discovered services&applications. Should respect victoria-logs replicas
• Grafana with pre-defined datasource to query&visualize logs from victoria-logs servers, and list of provisioned dashboards
• vmauth for balancing read requests among multiple replicas
• vmalert for running pre-defined and arbitrary alerting rules against victoria-logs servers
• alertmanager for accepting alerting notifications from vmalert