Add disabled compat for user config (#2833)

Treat <disabled> setting as equivalent to "null"
in keybindings user configs.

pkg/integration/tests/misc/disabled_keybindings.go

@@ -0,0 +1,26 @@
+package misc
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var DisabledKeybindings = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Confirms You can set keybindings to blank to disable them",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig: func(config *config.AppConfig) {
+		config.UserConfig.Keybinding.Universal.PrevItem = "<disabled>"
+		config.UserConfig.Keybinding.Universal.NextItem = "<disabled>"
+		config.UserConfig.Keybinding.Universal.NextTab = "<up>"
+		config.UserConfig.Keybinding.Universal.PrevTab = "<down>"
+	},
+	SetupRepo: func(shell *Shell) {},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Files().
+			IsFocused().
+			Press("<up>")
+
+		t.Views().Worktrees().IsFocused()
+	},
+})