neovim: deprecate programs.neovim.configure

[teto]

The configure option is not type checked and an artifact of how
nixpkgs is implemented.
We now have the equivalent options in home-manager and managing
interactions between the 2 systems complexifies maintainance of the
module.
Please use the other options at your disposal:
configure.packages..opt -> programs.neovim.plugins = [ { plugin = ...; optional = true; }]
configure.packages..start -> programs.neovim.plugins = [ { plugin = ...; }]
configure.customRC -> programs.neovim.extraConfig

Description

Checklist

• Change is backwards compatible.

• Code formatted with ./format.

• Code tested through nix-shell --pure tests -A run.all.

• Test cases updated/added. See example.

• Commit messages are formatted like

  {component}: {description}
  
  {long description}
  

  See CONTRIBUTING for more information and recent commit messages for examples.

• If this PR adds a new module

  • Added myself as module maintainer. See example.

  • Added myself and the module files to .github/CODEOWNERS.

[teto]

@thiagokokada does it "solve" your issue (providing that you (can) port the config)

[thiagokokada]

Well, I ported my config, so you can say this would "solve" it.