fix(defaults): skip rename_basename in document_symbols mapping

[jeffawang]

This fixes an issue where the document_symbols mode had an invalid mapping from the global map, ie. the ["b"] = "rename_basename" mapping.

The approach is to move the global mapping ["b"] = "rename_basename" mapping to each of the more specific git_status, buffers, and filesystem mappings, where they are valid.

Issue details

When pressing b in the document_symbols tree, I was getting this message:

[Neo-tree WARN] Invalid mapping for  b :  nil

And when pressing ? to see the keymap, I ran into this red error message:

E5108: Error executing lua: ...ng/.local/share/nvim/lazy/nui.nvim/lua/nui/line/init.lua:22: attempt to index local 'block' (a nil value)                                                                                                stack traceback:                                                                                                                                                                                                                                ...ng/.local/share/nvim/lazy/nui.nvim/lua/nui/line/init.lua:22: in function 'append'                                                                                                                                                    .../lazy/neo-tree.nvim/lua/neo-tree/sources/common/help.lua:62: in function 'show'
        ...y/neo-tree.nvim/lua/neo-tree/sources/common/commands.lua:891: in function <...y/neo-tree.nvim/lua/neo-tree/sources/common/commands.lua:888>

[pynappo]

I should've caught that earlier, my bad!