Add pad_start link formatting function #2505

[drewcorlin1]

Resolves #2505

Given a traceparent header like 00-00000000000000001b3ef83a5d15ed1b-61409d351b3a5d99-01, jaeger will store (and thus display + interpolate) the trace ID as 1b3ef83a5d15ed1b. When attempting to use the shortened trace ID to link to logs some tracing integrations (in my case, logs using pino instrumented with the OpenTelemetry pino instrumentation) will use the full length trace ID, making jaeger link patterns not work.

This PR adds a pad_start formatting function, heavily inspired by javascript's String.padStart to format the trace ID in those cases. If approved, I'll update the documentation in https://github.com/jaegertracing/documentation to mention this function and it's behavior.

In addition to this specific function, I'd like feedback on the approach of passing arguments to formatting functions with the space-delimited approach (eg #{traceID | padStart 32 0}).

How was this change tested?

Unit tests and by running it locally with the following UI config

const DEFAULT_CONFIG = {
  "linkPatterns": [
    {
      "type": "traces",
      "url": "https://myOpenSearch.com/_dashboards/app/discover#/?_g=(time:(from:'#{startTime | epoch_micros_to_date_iso}',to:'#{endTime | epoch_micros_to_date_iso}'))&_a=(columns:!(_source),filters:!(('$state':(store:appState),meta:(alias:!n,disabled:!f,index:filebeat-all,key:json.traceId,negate:!f,params:(query:'#{traceID | pad_start 32 0}'),type:phrase),query:(match_phrase:(json.traceId:'#{traceID | pad_start 32 0}')))),index:filebeat-all)",
      "text": "Logs"
    }
  ]
};

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.62%. Comparing base (d9315c6) to head (97069e3).
Report is 1 commits behind head on main.

Additional details and impacted files

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  Coverage   96.62%   96.62%           
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  Files         255      255           
  Lines        7697     7707   +10     
  Branches     2003     1990   -13     
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+ Hits         7437     7447   +10     
  Misses        260      260           

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[yurishkuro]

please add tests for edge cases

[drewcorlin1]

Add for this and for epoch_micros_to_date_iso