XML experimental support

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Opt-in SOAP/XML transport (xml feature) and examples consolidation

This release adds an experimental, opt-in SOAP/XML path for the core VIM APIs so clients can talk to targets (for example ESXi) where the VI JSON is not available, while keeping JSON as the default and preserving the existing public surface aside from a single builder addition. The examples workspace is simplified: shared connect and the former macro_examples binaries live under snippets, and utils / macro_examples are removed as separate members.

What changed

Library (vim_rs)

• Added optional Cargo feature xml and ClientBuilder::transport(TransportMode) with Json (default), Soap, and Auto.
• TransportMode::Auto tries the vCenter Hello System JSON API first, then falls back to SOAP/XML when that API is missing (enabling direct ESXi use cases).
• XML transport skips Hello System negotiation, so client.api_release() is no longer a negotiated capability signal on that path; service_content().about.api_version should be used for server capability decisions.
• Build impact when xml is enabled: roughly +500 KB release binary size and ~30–40% longer debug builds; default (feature off) matches prior behavior and costs.
• Caveat with xml enabled: manual polymorphic JSON deserialization requires _typeName before subtype-specific fields.

Known limitations (XML)

• VIM-only for now; VSAN, SPBM/PBM, SMS, VSLM, EAM error over XML.
• Treat as experimental; trace logs on vim_rs plus request/response captures help debug failures.

Examples

• Consolidate runnable samples into snippets; add snippets::connect (including optional VIM_PROTOCOL: auto / json / soap where applicable).
• Remove utils and macro_examples workspace packages; run examples with cargo run -p snippets --bin <name> from examples/ (see examples/README.md).

Documentation

• README.md and CHANGELOG.md updated to describe transport selection, caveats, and examples layout.

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This discussion was created from the release XML experimental support.