Add ``Consider-using-f-string`` checker (#4796)

* Add ``consider-using-f-string`` checker
This adds a checker for normal strings which are formatted
with ``.format()`` or '%'.
The message is a convention to nudge users towards using f-strings.
This closes #3592

* Update pylint code to use f-strings
After adding `consider-using-f-strings` the codebase showed numerous
cases of formatting which could be f-strings.
This commit changes most of these to become f-strings, or adds ignores.

* Apply suggestions from code review

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/pylint/message/message_definition.py b/pylint/message/message_definition.py
index a48526e9b..f7f680590 100644
--- a/pylint/message/message_definition.py
+++ b/pylint/message/message_definition.py
@@ -64,24 +64,24 @@ class MessageDefinition:
         """return the help string for the given message id"""
         desc = self.description
         if checkerref:
-            desc += " This message belongs to the %s checker." % self.checker_name
+            desc += f" This message belongs to the {self.checker_name} checker."
         title = self.msg
         if self.minversion or self.maxversion:
             restr = []
             if self.minversion:
-                restr.append("< %s" % ".".join(str(n) for n in self.minversion))
+                restr.append(f"< {'.'.join(str(n) for n in self.minversion)}")
             if self.maxversion:
-                restr.append(">= %s" % ".".join(str(n) for n in self.maxversion))
+                restr.append(f">= {'.'.join(str(n) for n in self.maxversion)}")
             restriction = " or ".join(restr)
             if checkerref:
-                desc += " It can't be emitted when using Python %s." % restriction
+                desc += f" It can't be emitted when using Python {restriction}."
             else:
                 desc += (
-                    " This message can't be emitted when using Python %s." % restriction
+                    f" This message can't be emitted when using Python {restriction}."
                 )
         msg_help = normalize_text(" ".join(desc.split()), indent="  ")
         message_id = f"{self.symbol} ({self.msgid})"
         if title != "%s":
             title = title.splitlines()[0]
-            return ":{}: *{}*\n{}".format(message_id, title.rstrip(" "), msg_help)
+            return f":{message_id}: *{title.rstrip(' ')}*\n{msg_help}"
         return f":{message_id}:\n{msg_help}"