chore: rebrand Nix to Lix when it makes sense

Here's my guide so far:

$ rg '((?!(recursive).*) Nix
(?!(daemon|store|expression|Rocks!|Packages|language|derivation|archive|account|user|sandbox|flake).*))'
-g '!doc/' --pcre2

All items from this query have been tackled. For the documentation side:
that's for https://git.lix.systems/lix-project/lix/issues/162.

Additionally, all remaining references to github.com/NixOS/nix which
were not relevant were also replaced.

Fixes: https://git.lix.systems/lix-project/lix/issues/148.
Fixes: https://git.lix.systems/lix-project/lix/issues/162.
Change-Id: Ib3451fae5cb8ab8cd9ac9e4e4551284ee6794545
Signed-off-by: Raito Bezarius <raito@lix.systems>

src/libstore/worker-protocol.cc

@@ -74,7 +74,7 @@ void WorkerProto::Serialise<DerivedPath>::write(const Store & store, WorkerProto
                     GET_PROTOCOL_MINOR(conn.version));
             },
             [&](std::monostate) {
-                throw Error("wanted to build a derivation that is itself a build product, but protocols do not support that. Try upgrading the Nix on the other end of this connection");
+                throw Error("wanted to build a derivation that is itself a build product, but protocols do not support that. Try upgrading the Nix implementation on the other end of this connection");
             },
         }, sOrDrvPath);
     }