feat: Host Metrics Generator

[shazlehu]

Proposed Change

To generate host metrics:

telemetrygeneratorreceiver:
    payloads_per_second: 1
    generators:
        - type: host_metrics
          resource_attributes:
            host.name: 2ed77de7e4c1
            os.type: linux     

To generate random metrics:

telemetrygeneratorreceiver:
    payloads_per_second: 1
    generators:
        - type: metrics
          resource_attributes:
            host.name: 2ed77de7e4c1
            os.type: linux          
          additional_config:
            metrics: 
            # memory metrics
             - name:	system.memory.usage
                value_min: 100000
                value_max: 1000000000
                type:	Sum
                unit:	By
                attributes:
                  state: cached
            # load metrics                  
              - name:	system.cpu.load_average.1m
                value_min: 0
                value_max: 1
                type: Gauge
                unit:	"{thread}"   
            # file system metrics                                          
              - name: system.filesystem.usage
                value_min: 0
                value_max: 15616700416
                type: Sum
                unit: By
                attributes:
                  device: "/dev/vda1"
                  mode: rw
                  mountpoint: "/etc/hosts"
                  state: reserved
                  type: ext4          

See README.md and sample_configs/metrics_config.yaml for additional details.

Checklist

• Changes are tested
• CI has passed