refactor!: update Telemetry Processor logic

[giortzisg]

Description

Refactoring the Telemetry Buffer to match this page https://develop.sentry.dev/sdk/telemetry/telemetry-processor/.
Changes include:

• naming changes to components to adhere to the spec
• separating envelopeItemConvertible to batchable and itemconvertible, so that we don't need to implement ToEnvelopeItem for a single log.
• delete unused ToEnvelopeItem(dsn)

Issues

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Changelog Entry

• refactor Telemetry Processor to use TelemetryItem instead of ItemConvertible
  • remove ToEnvelopeItem from single log items
  • rename TelemetryBuffer to Telemetry Processor to adhere to spec
  • remove unsed ToEnvelopeItem(dsn) from Event.

[github-actions]

Semver Impact of This PR

🔴 Major (breaking changes)

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Breaking Changes 🛠

• refactor Telemetry Processor to use TelemetryItem instead of ItemConvertible by giortzisg in #1180
  • remove ToEnvelopeItem from single log items
  • rename TelemetryBuffer to Telemetry Processor to adhere to spec
  • remove unsed ToEnvelopeItem(dsn) from Event.

New Features ✨

• Add metric support by aldy505 in #1151
  • support for three metric methods (counter, gauge, distribution)
  • custom metric units
  • unexport batchlogger

Internal Changes 🔧

Release

• Fix changelog-preview permissions by BYK in #1181
• Switch from action-prepare-release to Craft by BYK in #1167

Other

• (repo) Add Claude Code settings with basic permissions by philipphofmann in #1175
• Update release and changelog-preview workflows by giortzisg in #1177
• Bump echo to 4.10.1 by giortzisg in #1174

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