[prometheus-snmp-exporter] Add extraVolumes support and passing auth param

[tr3mor]

What this PR does / why we need it

This PR upgrades snmp exporter to version 0.24.1 which supports submitting config as multiple files (see https://github.com/prometheus/snmp_exporter/issues/628). This provides the ability to move the auth part into a separate file and load it separately as a secret (from Vault for example).

This PR also introduces support for extraVolumes and extraVolumeMounts to support this feature.

My use case for this feature: I have an init container that is responsible for getting the auth part of the config from the vault and needs to pass it to snmp-exporter, for this, I need to create an emptyDir volume and mount it to both containers. Also, it is quite a common feature to have for helm-charts with a lot of use cases in general.

Finally, this PR adds ability to specify auth query param to be passed to exporter via service monitor configuration (see https://github.com/prometheus/snmp_exporter/issues/619)

Special notes for your reviewer

Checklist

• [x] DCO signed
• [x] Chart Version bumped
• [x] Title of the PR starts with chart name (e.g. [prometheus-couchdb-exporter])