feat: suggest similar flags for an unknown flag

tea issue list --lable bug now fails with "unknown flag: --lable; did
you mean --label?". Suggestions are the command's visible flags that
start with the typed name or are at most two edits away from it.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/app_test.go

@@ -196,6 +196,22 @@ func TestRawJSONCommandsKeepJQToThemselves(t *testing.T) {
 	require.ErrorContains(t, root.Execute(), "raw prints text; --json is not supported")
 }
 
+func TestUnknownFlagsSuggestSimilarFlags(t *testing.T) {
+	requireUsageBeforeRequests(t, "unknown flag: --lable; did you mean --label?", "issue", "list", "--lable", "bug")
+	requireUsageBeforeRequests(t, "unknown flag: --stat; did you mean --state?", "issue", "list", "--stat", "open")
+	requireUsageBeforeRequests(t, "unknown flag: --add-label; did you mean --add-labels?", "issue", "edit", "1", "--add-label", "bug")
+	deps, _, _ := testDeps(t)
+	err := Execute(context.Background(), deps, []string{"issue", "list", "--zzzzzz"})
+	require.Equal(t, clierr.Usage, clierr.ExitCode(err))
+	require.EqualError(t, err, "unknown flag: --zzzzzz")
+	for _, tc := range []struct {
+		a, b     string
+		distance int
+	}{{"kitten", "sitting", 3}, {"", "abc", 3}, {"label", "label", 0}, {"lable", "label", 2}} {
+		require.Equal(t, tc.distance, editDistance(tc.a, tc.b), tc)
+	}
+}
+
 func TestRootHelpGroupsCommandsAndTopics(t *testing.T) {
 	deps, out, _ := testDeps(t)
 	require.NoError(t, Execute(context.Background(), deps, []string{"alias", "set", "co", "pr checkout"}))