feat: add mcfunction inlay hint support to LSP server

[Copilot]

This change adds first-class inlay hint support to the language server, focused on .mcfunction command arguments. The server now returns parameter-name hints for command inputs (including active subcommands in execute chains), improving readability of dense command lines.

• LSP capability + request handling

  • Added a new InlayHintService and registered it in server setup.
  • Advertises inlayHintProvider in initialize capabilities.
  • Wires textDocument/inlayHint via connection.languages.inlayHint.on(...).

• mcfunction hint generation

  • Parses each requested line as a command and resolves active subcommand context.
  • Maps parsed arguments to best-match command metadata and emits InlayHintKind.Parameter labels.
  • Excludes non-argument tokens (keyword, command, executeSubcommand) to avoid noisy hints.
  • Ignores empty/comment lines and returns hints only inside the requested range.

• Focused inlay-hint behavior coverage

  • Added unit coverage for:
    • basic argument hints (say hello world)
    • nested/execute subcommand hints
    • filtering of non-argument tokens
    • empty-input behavior

// Service registration
this.addDisposable(connection.languages.inlayHint.on(this.onInlayHint.bind(this)));

// Emitted hint shape
{
  kind: InlayHintKind.Parameter,
  label: `${hint.label}:`,
  paddingRight: true,
  position,
}