Vendor dprint plugins

[jakebailey]

We depend on these in our build for generated code. But, we are likely to hit firewall problems in the future since they get pulled from plugins.dprint.dev.

Instead, vendor copies in the repo, and add a script that can update them.

[Copilot]

Pull request overview

This PR vendors the dprint formatter WASM plugins into the repo to avoid format/check steps depending on fetching plugins from plugins.dprint.dev (which may fail under stricter network/firewall environments). It also adds a Hereby task to refresh the vendored plugins and records plugin version metadata.

Changes:

• Add a hereby update:dprint-plugins task that downloads the latest dprint plugin WASM files and writes _tools/dprint-plugins/versions.json.
• Update .dprint.jsonc to reference the vendored plugin WASM paths under _tools/dprint-plugins/.
• Adjust .gitignore to allow committing the vendored .wasm files and remove the Copilot setup prefetch step that previously pulled dprint caches.

Reviewed changes

Copilot reviewed 4 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
Herebyfile.mjs	Adds a task to download/update vendored dprint plugin WASM files and write plugin metadata.
.gitignore	Un-ignores the vendored _tools/dprint-plugins/*.wasm files so they can be committed.
.github/workflows/copilot-setup-steps.yml	Removes the previous step that attempted to prefetch dprint caches before network restrictions.
.dprint.jsonc	Switches dprint plugin configuration from remote URLs to local vendored WASM paths and documents the update task.
_tools/dprint-plugins/versions.json	Introduces metadata (version/checksum/url) for the vendored plugins.

[jakebailey]

dprint is getting "plugins via node_modules" so I'll hold off.