[mdatagen] Support logs

[sincejune]

Description

This PR introduces the foundational changes necessary for supporting logs data in the mdatagen tool.

mdatagen files for logs

This update includes the generation of generated_logs.go and generated_logs_test.go. These files are specifically for receiver and scraper components that support logs data, enabling initial log handling capabilities.

Introducing LogsBuilder

This PR introduced a LogsBuilder similar to the existing MetricsBuilder. It provides a structured way to manage log data with the following functions:

1. Emit(...ResourceLogsOption)
   Similar to Emit function in MetricsBuilder
2. EmitForResource(...ResourceLogsOption)
   Similar to EmitForResource function in MetricsBuilder
3. AppendLogRecord(plog.LogRecord)
   This function appends a log record to an internal buffer. The buffered log records are used to construct a ScopeLog when the Emit() or EmitForResource() functions are called. Scope name and version are automatically generated.

Next steps

• Add more test cases to LogsBuilder (e.g. reading test configs)
• Add LogsBuilderConfig to read logs property in metadata.yml to send structured logs
• Update receivers in contrib to use LogsBuilder.

Example usage:

lb := NewLogsBuilder(settings)

res := pcommon.NewResource()
res.Attributes().PutStr("region", "us-west-1")

// append the first log record
lr := plog.NewLogRecord()
lr.SetTimestamp(pcommon.NewTimestampFromTime(time.Now()))
lr.Attributes().PutStr("type", "log")
lr.Body().SetStr("the first log record")

// append the second log record
lr2 := plog.NewLogRecord()
lr2.SetTimestamp(pcommon.NewTimestampFromTime(time.Now()))
lr2.Attributes().PutStr("type", "event")
lr2.Body().SetStr("the second log record")

lb.AppendLogRecord(lr)
lb.AppendLogRecord(lr2)

logs := lb.Emit(WithLogsResource(res))

Example output:

resourceLogs:
  - resource:
      attributes:
        - key: region
          value:
            stringValue: us-west-1
    scopeLogs:
      - logRecords:
          - attributes:
              - key: type
                value:
                  stringValue: log
            body:
              stringValue: the first log record
            spanId: ""
            timeUnixNano: "1742291226022739000"
            traceId: ""
          - attributes:
              - key: type
                value:
                  stringValue: event
            body:
              stringValue: the second log record
            spanId: ""
            timeUnixNano: "1742291226022739000"
            traceId: ""
        scope:
          name: github.com/open-telemetry/opentelemetry-collector-contrib/receiver/awscloudwatchreceiver
          version: latest

Link to tracking issue

Part of #12571

Testing

Added

Documentation

Added

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.59%. Comparing base (12dd09f) to head (ab14c7a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12659      +/-   ##
==========================================
+ Coverage   91.55%   91.59%   +0.04%     
==========================================
  Files         480      483       +3     
  Lines       26391    26504     +113     
==========================================
+ Hits        24162    24277     +115     
+ Misses       1766     1763       -3     
- Partials      463      464       +1     

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