Add attribute APIs to Scope class

[Lms24]

Problem Statement

ref: https://linear.app/getsentry/issue/SDK-46/new-global-attributes-api-on-the-scope

As per https://develop.sentry.dev/sdk/telemetry/scopes/#setting-attributes, the Scope class should implement setAttribute(s) APIs.

Solution Brainstorm

Implement it as a first step, apply to logs, metrics, span envelopes afterwards

Additional Context

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[linear]

JS-1140

[github-actions]

A PR closing this issue has just been released 🚀

This issue was referenced by PR #18165, which was included in the 10.27.0 release.