key and cat: no need for progressBar

otherwise the output will be invisible in common terminal configurations

src/nix/cat.cc

@@ -1,6 +1,7 @@
 #include "command.hh"
 #include "store-api.hh"
 #include "nar-accessor.hh"
+#include "progress-bar.hh"
 
 using namespace nix;
 
@@ -13,6 +14,7 @@ struct MixCat : virtual Args
         auto st = accessor->lstat(CanonPath(path));
         if (st.type != SourceAccessor::Type::tRegular)
             throw Error("path '%1%' is not a regular file", path);
+        stopProgressBar();
         writeFull(STDOUT_FILENO, accessor->readFile(CanonPath(path)));
     }
 };

src/nix/sigs.cc

@@ -3,6 +3,7 @@
 #include "shared.hh"
 #include "store-api.hh"
 #include "thread-pool.hh"
+#include "progress-bar.hh"
 
 #include <atomic>
 
@@ -174,6 +175,7 @@ struct CmdKeyGenerateSecret : Command
         if (!keyName)
             throw UsageError("required argument '--key-name' is missing");
 
+        stopProgressBar();
         writeFull(STDOUT_FILENO, SecretKey::generate(*keyName).to_string());
     }
 };
@@ -195,6 +197,7 @@ struct CmdKeyConvertSecretToPublic : Command
     void run() override
     {
         SecretKey secretKey(drainFD(STDIN_FILENO));
+        stopProgressBar();
         writeFull(STDOUT_FILENO, secretKey.toPublicKey().to_string());
     }
 };