Add Long Tasks API as spans

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Ref: https://developer.mozilla.org/en-US/docs/Web/API/Long_Tasks_API

[github-actions]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you label it Status: Backlog or Status: In Progress, I will leave it alone ... forever!

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"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀

[AbhiPrasad]

Some work done in the Sentry frontend:

• Adding long tasks observer ref(sdk): Add temp long task check inside VCD sentry#32072
• Adding long tasks app-wide ref(perf): Move long-tasks to app-wide sentry#33614
• Adding long tasks info as measurements feat(perf): Add long task information as measurements sentry#36026