Makes explorer and desktop sibling projects, as proposed in ADR 1.
This commit only moves files; paths in CI, scripts and docs are fixed
in the following commits.
Use this script to update tests/support/heartwood-version and keep the
flake in sync with it.
Alternatively, run the script as
scripts/update-flake $(cat tests/support/heartwood-version)
to bring the flake back into sync.
This also updates the flake.lock and the updates the state of the npm
dependencies when run from a nix-enabled system.
Rūdolfs Ošiņš