* Fix `buildIdris` on non-macos machines
We build the support library as its own derivation for Nix builds so we do not want to copy it as part of the `buildIdris` install phase and we certainly don't want to wrap it as if it were an executable.
* Update nix/buildIdris.nix
* Refactor buildIdris slightly and support installing libraries with source. Add the Idris2 API package as an output of the flake.
* update templates and simplify construction of a search path.
* use newer method of specifying default package
* swap out trace function for warn function. fix warnings in template generation
