scripted-diff: Rename PACKAGE_* variables to CLIENT_*

This change ensures consistent use of the `CLIENT_` namespace everywhere
in the repository.

-BEGIN VERIFY SCRIPT-

ren() { sed -i "s/\<$1\>/$2/g" $( git grep -l "$1" ./cmake ./src :\(exclude\)./src/secp256k1 ./test ) ; }

ren PACKAGE_NAME      CLIENT_NAME
ren PACKAGE_VERSION   CLIENT_VERSION_STRING
ren PACKAGE_URL       CLIENT_URL
ren PACKAGE_BUGREPORT CLIENT_BUGREPORT

-END VERIFY SCRIPT-

test/functional/test_framework/test_framework.py

@@ -349,7 +349,7 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
             self.log.error("Hint: Call {} '{}' to consolidate all logs".format(os.path.normpath(os.path.dirname(os.path.realpath(__file__)) + "/../combine_logs.py"), self.options.tmpdir))
             self.log.error("")
             self.log.error("If this failure happened unexpectedly or intermittently, please file a bug and provide a link or upload of the combined log.")
-            self.log.error(self.config['environment']['PACKAGE_BUGREPORT'])
+            self.log.error(self.config['environment']['CLIENT_BUGREPORT'])
             self.log.error("")
             exit_code = TEST_EXIT_FAILED
         # Logging.shutdown will not remove stream- and filehandlers, so we must