test: enable bootstrap contract tests

[joker23]

This PR will enable the new bootstrap tests on client side sdks that support bootstrapping

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Note

Overview
Enables bootstrap contract tests across client-side JS SDK harnesses by advertising the capability and forwarding harness configuration into client initialization.

SDKConfigClientSideParams now includes optional bootstrap. Browser, Node, React, Vue, and React Native contract-test adapters read clientSide.bootstrap and pass it into client.start() (or identify() on React Native) when present. Each harness also adds 'bootstrap' to its reported capabilities (and the Node service capability list).

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[github-actions]

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 29603 bytes
Compressed size limit: 30000
Uncompressed size: 142116 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 32662 bytes
Compressed size limit: 34000
Uncompressed size: 117055 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 25437 bytes
Compressed size limit: 44000
Uncompressed size: 165420 bytes

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.