fcft: refactor derivation
fcft: refactor derivation

* Change from fetchzip to fetchFromGitea.
* Set `mesonBuildType` instead of supplying the --build-type=
  argument in `mesonFlags` as the build type option will be
  repeated.
* Abstact optional flag declaration with a helper function.
* Add upstream changelog.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs