Put gcroots in own directory first

Dependencies

• [2] KLDNEAB5 Rename 06-windows -> 06-windows-wine
• [3] FYBNOJLT Automagically add --rebuild to nix build commands in interactive mode
• [4] WNFTZY3M Optionally prevent relevant nix store paths from being GC'ed
• [5] U6EHWR7Y Tweak --gcroots
• [*] W2G433QU Refactor libdemo and flakeref for nix run commands
• [*] ZV5WPO25 Extend 02

Change contents

• replacement in bash/nix-container-demo-helper.sh at line 33
  [4.1010]→[4.1010:1071](∅→∅)
  − __nix_gcroot_dir="/nix/var/nix/gcroots/per-user/${USER}"
  [4.1010]

  [4.1071]
  + __nix_gcroot_local_dir="$(dirname "${BASH_SOURCE[0]}")/../gcroots"

  + __nix_gcroot_store_dir="/nix/var/nix/gcroots/per-user/${USER}"
• edit in bash/nix-container-demo-helper.sh at line 40
  [3.106]

  [3.106]
  + local -r suffix="$(basename "${storepath}")"
• replacement in bash/nix-container-demo-helper.sh at line 42
  [3.158]→[3.158:333](∅→∅)
  − local -r gcroot="${__nix_gcroot_dir}/${__nix_gcroot_prefix}-$(basename "${storepath}")"

  − rm -f "${gcroot}"

  − ln -s "${storepath}" "${gcroot}"
  [3.158]

  [3.333]
  + mkdir -p "${__nix_gcroot_local_dir}"

  + local -r gcroot_local="$(realpath --no-symlinks "${__nix_gcroot_local_dir}/${__nix_gcroot_prefix}-${suffix}")"

  + rm -f "${gcroot_local}"

  + ln -s "${storepath}" "${gcroot_local}"

  + local -r gcroot_store="${__nix_gcroot_store_dir}/${__nix_gcroot_prefix}-${suffix}"

  + rm -f "${gcroot_store}"

  + ln -s "${gcroot_local}" "${gcroot_store}"
• replacement in bash/nix-container-demo-helper.sh at line 54
  [4.1289]→[4.1289:1397](∅→∅)
  − find "${__nix_gcroot_dir}" -name "${__nix_gcroot_prefix}-*" -print | sed "s|${__nix_gcroot_dir}/||"
  [4.1289]

  [4.1397]
  + find "${__nix_gcroot_store_dir}" -name "${__nix_gcroot_prefix}-*" -print | sed "s|${__nix_gcroot_store_dir}/||"
• replacement in bash/nix-container-demo-helper.sh at line 60
  [4.1502]→[4.1502:1578](∅→∅)
  − find "${__nix_gcroot_dir}" -name "${__nix_gcroot_prefix}-*" -delete
  [4.1502]

  [4.909]
  + find "${__nix_gcroot_store_dir}" -name "${__nix_gcroot_prefix}-*" -delete
• edit in .gitignore at line 5
  [2.167]
  +

  + /gcroots