Multi Instance: Refactor: remove simple core.get_explorer() usages

• #2255

core.get_explorer() is not possible in a multi instance world. An Explorer instance should always be available and used.

Remove usages, replacing with:

• explorer from node or containing class
• explorer passed from the caller
• node.explorer passed from the caller

If the replacement is non-trivial or would require the caller to be converted to an explorer member class please:

• skip it
• mention it in a comment on this issue
• raise a new issue similar to #2829 (situational)

Usages at 2025-03-21

lua/nvim-tree/actions/finders/find-file.lua
lua/nvim-tree/actions/finders/search-node.lua
lua/nvim-tree/actions/fs/create-file.lua
lua/nvim-tree/actions/fs/remove-file.lua
lua/nvim-tree/actions/fs/rename-file.lua
lua/nvim-tree/actions/fs/trash.lua
lua/nvim-tree/actions/moves/item.lua
lua/nvim-tree/actions/moves/sibling.lua
lua/nvim-tree/actions/root/change-dir.lua
lua/nvim-tree/actions/tree/find-file.lua
lua/nvim-tree/actions/tree/modifiers/collapse-all.lua
lua/nvim-tree/actions/tree/modifiers/expand-all.lua
lua/nvim-tree/api.lua
lua/nvim-tree/diagnostics.lua
lua/nvim-tree/lib.lua
lua/nvim-tree/utils.lua
lua/nvim-tree/view.lua