feat(vim): rework vim plugin with lsp client. bump version to 2.0.0-dev.

[icycodes]

Notable Changes in vim-tabby Plugin 2.0

Since version 2.0, the vim-tabby plugin is designed as two parts:

1. LSP Client Extension:
   • Relies on an LSP client and extends it with methods (such as textDocument/inlineCompletion) to communicate with the tabby-agent.
2. Inline Completion UI:
   • Automatically triggers inline completion requests when typing.
   • Renders the inline completion text as ghost text.
   • Sets up actions with keyboard shortcuts to accept or dismiss the inline completion.

Requirements Changes

• The Node.js script of tabby-agent is no longer a built-in part of the vim-tabby plugin. You need to install tabby-agent separately via npm, and the LSP client will launch it using the command npx tabby-agent --stdio.
• Requires a LSP client. The Neovim built-in LSP client, or a Vim plugin that provides an LSP client.

Supported LSP clients

• The Neovim built-in LSP client, with the nvim-lspconfig plugin installed.
• More clients are in development.