Make mini.nvim ignore git ignored files.

Based off of
31f7988420
(thanks)

.config/nvim/lua/plugin/mini.lua

@@ -69,7 +69,38 @@ require('mini.diff').setup({ -- shows git diffs in the file
 		style = 'sign',
 	}
 })
-require('mini.files').setup()      -- file browser
+require('mini.files').setup({ -- file browser
+	content = {
+		-- Sort is faster than content.filter, since git is invoked once.
+		sort = function(entries)
+			-- Prepare the paths for sending via STDIN later.
+			local pats = table.concat(vim.iter(entries)
+				:map(function(e) return e.path end):totable(), '\n')
+
+			-- Open up the git command, where we will send the list over STDIN
+			local out = {}
+			local id = vim.fn.jobstart({ "git", "check-ignore", "--stdin" }, {
+				stdout_buffered = true,
+				on_stdout = function(_, dat) out = dat end
+			})
+
+			-- Return the entries if the command failed
+			if id < 1 then return entries end
+
+			-- Send the lines over STDIN, and await a response.
+			vim.fn.chansend(id, pats)
+			vim.fn.chanclose(id, 'stdin')
+			vim.fn.jobwait({ id })
+
+			-- This response is used to filter out everything that was sent back;
+			-- I.e. should be ignored.
+			return require("mini.files").detault_sort(
+				vim.iter(entries):filter(function(e)
+					return not vim.tbl_contains(out, e.path)
+				end):totable())
+		end
+	}
+})
 Map('n', '<leader>o', MiniFiles.open, { desc = "Open mini file browser" })
 require('mini.jump').setup()       -- extends f,F,t,T to work across multiple lines
 require('mini.cursorword').setup() -- highlight words beneath the cursor