feature: Override neovim buffer commands & keymaps

Did you check the docs?

• I have read all the vscode-neovim docs
• I understand the fundamental limitations of the plugin and believe this request to be reasonable

Is your feature request related to a problem? Please describe.

The current plugin only supports tab management. Considering that the tabs in VSCode are actually similar to the buffer concept in Neovim, it is valid to support buffer-related commands and keymaps to align with the behavior and operation experience of Neovim. Emmm, just a thought.

Describe the solution you'd like

Consider support buffer commands(e.g. :bd, :bn, :bp) & buffer keymaps(e.g. ]b, [b).

Describe alternatives you've considered

None.

Additional context

No response