Ground work to make the evaluation logic more clearly separated from
the deployment logic.
The `colmenaHive` output will be the integration point between the two
halves.
This seems to be the easiest way to get pure-eval working with
existing evaluation mechinery (nix-instantiate, nix-eval-jobs).
Now `--pure-eval` is forced for flakes with user being able to
add `--impure` as needed.
- the reason for this change is to have more transparent separation
of concern between effectuations of the module system and pre-module
system effectuations
- with improved flakes support down the line, pre-module system
effectuations will get more complex
- this also allows to patch the aspects of the evaluation individually
while tracking other components from upstream. eg. path options & eval
but not modules
`eval-config.nix` will set the canonical path for us that will then be used
to strip the module path prefixes in `nixos/modules/misc/documentation.nix` [1].
This should fix split docs build problems described in #50.
[1] 1511e72b75/nixos/modules/misc/documentation.nix (L79)
Allow flake users to import .#nixosModules.deploymentOptions
into their flake, so that the same expression can be used for both,
.#colmena.$host as well as .#nixosConfiguration.$host, without the
latter complaining about undefined options in "deployment".
This partially addresses #33, and allows Colmena to be used more
easily on bandwidth-constrained hosts and macOS.
With `deployment.buildOnTarget = true;` deployment works fine from
macOS without designated builders, except when IFD is involved.
This makes evaluation faster especially when `nodes` is heavily used in
the configuration (like in my auto-meshing setup). This matches the
behavior of Morph.
