Golang runtime observ lib

[v-zhuravlev]

This lib can produce panels/rows and dashboards for both Golang instrumentation types:

1. prometheus
2. otel

As input, this lib uses commonlib 'signals' that describe which KPI we want to track. Than we can quickly use commonlib signals package to transform signals to panels of different types (timeseries,stat...), panelMixins(targets+overrides) or targets.

Results of this observability library (panesl/rows) can be used together to compose other dashboards.

This PR also refactors signal libs:

• move common parts to base file
• add rangeFunction to change defaults rate() function to irate,delta,idelta and so on.
• add new unmarshallJsonNew() func to parse new json form of signals
• add legendCustomTemplate to completely override default legend generated