Support range select for staging/discarding files

As part of this, you must now press enter on a merge conflict file
to focus the merge view; you can no longer press space and if you do
it will raise an error.

pkg/integration/tests/file/discard_various_changes_range_select.go

@@ -0,0 +1,69 @@
+package file
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var DiscardVariousChangesRangeSelect = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Discarding all possible permutations of changed files via range select",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig: func(config *config.AppConfig) {
+	},
+	SetupRepo: func(shell *Shell) {
+		createAllPossiblePermutationsOfChangedFiles(shell)
+	},
+
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Files().
+			IsFocused().
+			Lines(
+				Contains("UA").Contains("added-them-changed-us.txt").IsSelected(),
+				Contains("AA").Contains("both-added.txt"),
+				Contains("DD").Contains("both-deleted.txt"),
+				Contains("UU").Contains("both-modded.txt"),
+				Contains("AU").Contains("changed-them-added-us.txt"),
+				Contains("UD").Contains("deleted-them.txt"),
+				Contains("DU").Contains("deleted-us.txt"),
+			).
+			Press(keys.Universal.ToggleRangeSelect).
+			NavigateToLine(Contains("deleted-us.txt")).
+			Press(keys.Universal.Remove).
+			Tap(func() {
+				t.ExpectPopup().Menu().
+					Title(Equals("Discard changes")).
+					Select(Contains("Discard all changes")).
+					Confirm()
+
+				t.ExpectPopup().Confirmation().
+					Title(Equals("Continue")).
+					Content(Contains("All merge conflicts resolved. Continue?")).
+					Cancel()
+			}).
+			Lines(
+				Contains("AM").Contains("added-changed.txt").IsSelected(),
+				Contains("MD").Contains("change-delete.txt"),
+				Contains("D ").Contains("delete-change.txt"),
+				Contains("D ").Contains("deleted-staged.txt"),
+				Contains(" D").Contains("deleted.txt"),
+				Contains("MM").Contains("double-modded.txt"),
+				Contains("M ").Contains("modded-staged.txt"),
+				Contains(" M").Contains("modded.txt"),
+				Contains("A ").Contains("new-staged.txt"),
+				Contains("??").Contains("new.txt"),
+				Contains("R ").Contains("renamed.txt → renamed2.txt"),
+			).
+			Press(keys.Universal.ToggleRangeSelect).
+			NavigateToLine(Contains("renamed.txt")).
+			Press(keys.Universal.Remove).
+			Tap(func() {
+				t.ExpectPopup().Menu().
+					Title(Equals("Discard changes")).
+					Select(Contains("Discard all changes")).
+					Confirm()
+			})
+
+		t.Views().Files().IsEmpty()
+	},
+})