[default.nix] Add coq-version, meta.platform and setupHook.
[default.nix] Add coq-version, meta.platform and setupHook.

Closes #8227 by solving remaining differences.

Sets dontFilter in anticipation of NixOS/nixpkgs#49456.

gares/coq,silene/coq,maximedenes/coq,coq/coq,Zimmi48/coq,SkySkimmer/coq,maximedenes/coq,ejgallego/coq,ppedrot/coq,silene/coq,ejgallego/coq,coq/coq,maximedenes/coq,gares/coq,Zimmi48/coq,SkySkimmer/coq,Matafou/coq,Matafou/coq,Matafou/coq,Zimmi48/coq,SkySkimmer/coq,ppedrot/coq,JasonGross/coq,ppedrot/coq,gares/coq,JasonGross/coq,ppedrot/coq,SkySkimmer/coq,JasonGross/coq,maximedenes/coq,ejgallego/coq,ppedrot/coq,ejgallego/coq,Zimmi48/coq,gares/coq,silene/coq,coq/coq,maximedenes/coq,gares/coq,coq/coq,JasonGross/coq