Restructure Darwin configuration

So far, this is just based on mightymac. The other devices will be
updated soon.

modules/hosts/common/files/nvim/lua/plugins/bufferline.lua

@@ -0,0 +1,49 @@
+return {
+  "akinsho/bufferline.nvim",
+  after = "catppuccin",
+  dependencies = { "nvim-tree/nvim-web-devicons" },
+  version = "*",
+  config = function()
+    -- Get the color pallet of the theme flavor I am using
+    local color_palette = require("catppuccin.palettes").get_palette("frappe")
+
+    -- Set variables to use the color they'd use if the background was not transparent
+    local bg_highlight = color_palette.crust
+    local separator_fg = color_palette.crust
+
+    require("bufferline").setup({
+      highlights = require("catppuccin.groups.integrations.bufferline").get({
+        -- Copy settings from Catppuccin bufferline integration and override just the
+        -- part that is  needed to make it look like it would if the background was not
+        -- set to transparent in catppuccin.lua
+        -- https://github.com/catppuccin/nvim/blob/main/lua/catppuccin/groups/integrations/bufferline.lua
+        custom = {
+          all = {
+            -- this makes the background behind the tabs contrast with the tabs themselves
+            fill = { bg = bg_highlight },
+
+            -- separators
+            -- I am only overriding the foreground as that is what makes the tabs look correct
+            separator = { fg = separator_fg },
+            separator_visible = { fg = separator_fg },
+            separator_selected = { fg = separator_fg },
+            offset_separator = { fg = separator_fg },
+          },
+        },
+      }),
+      options = {
+        mode = "buffers",
+        separator_style = "slant",
+        offsets = {
+          {
+            filetype = "neo-tree",
+            text = "File Explorer",
+            highlight = "Directory",
+            separator = true,
+          },
+        },
+        diagnostics = "nvim_lsp",
+      },
+    })
+  end,
+}