Add nvm/asdf support

Right now node/npm are always downloaded. It would be nice if they used nvm and/or asdf when they are available.

Start in the Gradle plugins' node/npm download and setup entry points, then inspect how the required runtime versions are selected. Define done as using nvm or asdf when available while preserving the existing download behavior when neither is present; no specific files or tests are named in the issue.

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