Add interface to access V8-only error method.

[ditman]

Description

Add interface to access V8-only error method.

(Unblocks cl/880945339)

Pre-launch Checklist

• I signed the CLA.
• I read the Contributors Guide.
• I read the Style Guide.
• I have added updates to the CHANGELOG.
• I updated/added relevant documentation.
• My code changes (if any) have tests.

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[gemini-code-assist]

Code Review

The pull request updates the package version to 0.8.5 and introduces a V8ErrorConstructor interface to correctly type and access the V8-specific captureStackTrace method on the Error object within the A2uiError class, improving type safety. A review comment suggests an improvement to use the 'captureStackTrace' in Error operator for checking property existence, which is more idiomatic and readable than casting Error within the conditional.

[ditman]

(Actually, I'm going to duplicate this error class into the v0_8 renderer, so there's no need to cross import from 0_9 into 0_8)

[ditman]

PTAL @gspencergoog, I duplicated the errors.js class into 0_8 so we don't need to take a dependency from 0_9 just for the errors class (that was the only instance I could find where we're importing from 0_9 into 0_8)