feat(nvim): use conform to format Lua files

This is replacing using formatprg to run the same program (stylua), this
has extra benefits.

Conform has the ability to run automatically on save, but this is
currently using `formatexpr` to run on demand using `gq`.

nvim/after/ftplugin/lua.lua

@@ -1,10 +1,5 @@
 -- Tabs should have 4 space width.
 vim.opt_local.tabstop = 4
 
--- Use stylua as formatter if it is available.
-if vim.fn.executable("stylua") == 1 then
-	vim.opt_local.formatprg = "stylua --stdin-filepath % --search-parent-directories -"
-end
-
 -- Use luacheck as compiler for sh files.
 vim.cmd([[compiler luacheck]])

nvim/after/plugin/conform.lua

@@ -0,0 +1,7 @@
+local options = {
+	formatters_by_ft = {
+		lua = { "stylua" },
+	},
+}
+
+require("conform").setup(options)

nvim/after/plugin/lsp.lua

@@ -65,8 +65,5 @@ vim.api.nvim_create_autocmd("LspAttach", {
 		vim.keymap.set("n", "<localleader>rn", vim.lsp.buf.rename, opts)
 		vim.keymap.set({ "n", "v" }, "<localleader>ca", vim.lsp.buf.code_action, opts)
 		vim.keymap.set("n", "gr", vim.lsp.buf.references, opts)
-		vim.keymap.set("n", "<localleader>f", function()
-			vim.lsp.buf.format({ async = true })
-		end, opts)
 	end,
 })

nvim/lua/dcp/keymaps.lua

@@ -22,6 +22,13 @@
 vim.g.mapleader = "\\"
 vim.g.maplocalleader = " "
 
+-- Leader,a series acts on the whole file.
+--
+-- Leader,ai indents the whole file.
+vim.keymap.set("n", "<Leader>ai", "mzgg=G`z")
+-- Leader,af formats the whole file.
+vim.keymap.set("n", "<Leader>af", "mzgggqG`z")
+
 -- Leader,b list all open buffers.
 vim.keymap.set("n", "<Leader>b", ":buffer <C-d>")