constify some objects to remove copies

7 jobs for outline-modification in 4 minutes and 23 seconds
Status Job ID Name Coverage
  Build
passed #10681714
build

00:03:35

passed #10681719
build_android

00:03:07

passed #10681715
build_clang12_libcpp

00:04:21

passed #10681718
build_clazy_clang12

00:02:43

passed #10681717
build_mingw64_fedora34

00:02:02

passed #10681716
build_ubuntu_18_04

00:01:33

passed #10681713
clang_format

00:00:58