Add UBNT AirOS module (older firmware) and other

[v-zhuravlev]

1. Add module handy for UBNT AirOS.

Will be used for snmp-observ-lib(mixin) here:
https://github.com/grafana/jsonnet-libs/pull/1382/files#diff-d053bf7f667576c028f9c8a0b1ec7248b5963dcea3f9db7f87b8ddb75ede9a48R101

Sample response with CPU+mem:

# HELP loadValue The 1,5 and 10 minute load averages - 1.3.6.1.4.1.10002.1.1.1.4.2.1.3
# TYPE loadValue gauge
loadValue{loadDescr="1 Minute Average",loadIndex="1"} 12
loadValue{loadDescr="15 Minute Average",loadIndex="3"} 2
loadValue{loadDescr="5 Minute Average",loadIndex="2"} 64
# HELP memBuffer Physical memory used by buffers (in KB) - 1.3.6.1.4.1.10002.1.1.1.1.3
# TYPE memBuffer gauge
memBuffer 2308
# HELP memCache Physical memory used for caching (in KB) - 1.3.6.1.4.1.10002.1.1.1.1.4
# TYPE memCache gauge
memCache 0
# HELP memFree Available physical memory (in KB) - 1.3.6.1.4.1.10002.1.1.1.1.2
# TYPE memFree gauge
memFree 42576
# HELP memTotal Total usable physical memory (in KB) - 1.3.6.1.4.1.10002.1.1.1.1.1
# TYPE memTotal gauge
memTotal 62268
# HELP snmp_scrape_duration_seconds Total SNMP time scrape took (walk and processing).
# TYPE snmp_scrape_duration_seconds gauge
snmp_scrape_duration_seconds{module="ubiquiti_airos"} 0.041145583
# HELP snmp_scrape_packets_retried Packets retried for get, bulkget, and walk.
# TYPE snmp_scrape_packets_retried gauge
snmp_scrape_packets_retried{module="ubiquiti_airos"} 0
# HELP snmp_scrape_packets_sent Packets sent for get, bulkget, and walk; including retries.
# TYPE snmp_scrape_packets_sent gauge
snmp_scrape_packets_sent{module="ubiquiti_airos"} 2
# HELP snmp_scrape_pdus_returned PDUs returned from get, bulkget, and walk.
# TYPE snmp_scrape_pdus_returned gauge
snmp_scrape_pdus_returned{module="ubiquiti_airos"} 13
# HELP snmp_scrape_walk_duration_seconds Time SNMP walk/bulkwalk took.
# TYPE snmp_scrape_walk_duration_seconds gauge
snmp_scrape_walk_duration_seconds{module="ubiquiti_airos"} 0.040930083

2. Add module for D-Link Switches like D-LINK DES/DGS 3200-xx:

Draft mixin example: https://github.com/grafana/jsonnet-libs/pull/1382/files#diff-b6afb60ecef31523e91401ffe4a3ad295af027e257e2d98fc9f0e9360084f3edR64

Sample response with CPU+mem:

# HELP agentCPUutilizationIn1min Time scale is 1 minute.The value will be between 0%(idle) and 100% (very busy). - 1.3.6.1.4.1.171.12.1.1.6.2
# TYPE agentCPUutilizationIn1min gauge
agentCPUutilizationIn1min 0
# HELP agentCPUutilizationIn5min Time scale is 5 minute.The value will be between 0%(idle) and 100% (very busy). - 1.3.6.1.4.1.171.12.1.1.6.3
# TYPE agentCPUutilizationIn5min gauge
agentCPUutilizationIn5min 28
# HELP agentCPUutilizationIn5sec Time scale is 5 seconds.The value will be between 0%(idle) and 100% (very busy). - 1.3.6.1.4.1.171.12.1.1.6.1
# TYPE agentCPUutilizationIn5sec gauge
agentCPUutilizationIn5sec 30
# HELP agentDRAMutilization The percentage of used DRAM memory of the total DRAM memory available - 1.3.6.1.4.1.171.12.1.1.9.1.4
# TYPE agentDRAMutilization gauge
agentDRAMutilization{agentDRAMutilizationUnitID="0"} 88
# HELP agentDRAMutilizationTotalDRAM The size of Total DRAM Memory. - 1.3.6.1.4.1.171.12.1.1.9.1.2
# TYPE agentDRAMutilizationTotalDRAM gauge
agentDRAMutilizationTotalDRAM{agentDRAMutilizationUnitID="0"} 131072
# HELP agentDRAMutilizationUsedDRAM The size of used DRAM memory. - 1.3.6.1.4.1.171.12.1.1.9.1.3
# TYPE agentDRAMutilizationUsedDRAM gauge
agentDRAMutilizationUsedDRAM{agentDRAMutilizationUnitID="0"} 115908
# HELP snmp_scrape_duration_seconds Total SNMP time scrape took (walk and processing).
# TYPE snmp_scrape_duration_seconds gauge
snmp_scrape_duration_seconds{module="dlink"} 0.107122
# HELP snmp_scrape_packets_retried Packets retried for get, bulkget, and walk.
# TYPE snmp_scrape_packets_retried gauge
snmp_scrape_packets_retried{module="dlink"} 0
# HELP snmp_scrape_packets_sent Packets sent for get, bulkget, and walk; including retries.
# TYPE snmp_scrape_packets_sent gauge
snmp_scrape_packets_sent{module="dlink"} 2
# HELP snmp_scrape_pdus_returned PDUs returned from get, bulkget, and walk.
# TYPE snmp_scrape_pdus_returned gauge
snmp_scrape_pdus_returned{module="dlink"} 7
# HELP snmp_scrape_walk_duration_seconds Time SNMP walk/bulkwalk took.
# TYPE snmp_scrape_walk_duration_seconds gauge
snmp_scrape_walk_duration_seconds{module="dlink"} 0.107086208

3. Eltex MES switch CPU&memory.
   mixin draft: https://github.com/grafana/jsonnet-libs/pull/1382/files#diff-d053bf7f667576c028f9c8a0b1ec7248b5963dcea3f9db7f87b8ddb75ede9a48R67

[RichiH]

If there is no other source, I think it's defensible

[bastischubert]

LGTM