* feat(keymaps.lua): add new keymaps for various actions
* feat(treesitter.lua): add treesitter configuration for terraform language
* chore(init.lua): comment out unused keymap for signature help
* feat(plugins): add undotree plugin
* feat(plugins): add lsp_signature plugin and setup configuration
* feat(bufferline.lua): add configuration for bufferline plugin with options for indicator, diagnostics, offsets, separator_style, and always_show_bufferline