Previously only extraLuaPackages themselves were byte-compiled, not
theirs dependencies. This commit fixes that by compiling lua packages
recursively. It uses byte-compile-lua-lib.nix shared file.
Also this commit uses the shared stub lua libraries for extraLuaPackages
byte-compiling test.
This commit replaces custom lua plugins in tests with shared stub
plugins from utils module.
After this change the test has started to fail. Debugging this issue
I found out that dependencies of plugins weren't processed.
This commit improves the test assertion to detect duplicated
dependencies in this case and fixes the underlying issue by also
processing dependencies.
