feat: add OpenSandbox sandbox provider

[dargoner]

AgentScope-Java Version

2.0.3-SNAPSHOT

Description

Add the original OpenSandbox sandbox adapter as a standalone sandbox extension.

• Add the OpenSandbox Java SDK dependency and extension module wiring.
• Implement sandbox lifecycle management, shell execution, file transfer, and state serialization.
• Add OpenSandbox filesystem integration and Harness Jackson support.
• Add unit, integration, and serialization coverage.
• Update English and Chinese sandbox documentation and integration module lists.

Testing

• mvnd -pl :agentscope-extensions-sandbox-opensandbox -am package -DskipTests (passed)
• Test execution was skipped in the local Windows environment.

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

❌ Patch coverage is 95.29703% with 19 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...pe/extensions/sandbox/opensandbox/OpenSandbox.java	90.75%	4 Missing and 7 partials ⚠️
...ns/sandbox/opensandbox/OfficialOpenSandboxSdk.java	95.65%	0 Missing and 3 partials ⚠️
...ensions/sandbox/opensandbox/OpenSandboxClient.java	96.66%	0 Missing and 2 partials ⚠️
.../sandbox/opensandbox/OpenSandboxClientOptions.java	97.10%	0 Missing and 2 partials ⚠️
...sions/sandbox/opensandbox/OpenSandboxEndpoint.java	92.85%	0 Missing and 1 partial ⚠️

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