Apply suggestions from code review

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: shugo

sig/lib/textbringer/commands/files.rbs

@@ -5,9 +5,7 @@ module Textbringer::Commands
 
   def find_file_read_only: (?String) -> nil
 
-  def find_source: (?TestFiles) -> Array[untyped]
-                 | (?Class) -> Array[untyped]
-                 | (?untyped) -> Array[untyped]
+  def find_source: (?untyped) -> Array[untyped]
 
   def make_directory: (?String) -> Array[untyped]
 

sig/lib/textbringer/commands/keyboard_macro.rbs

@@ -20,7 +20,6 @@ module Textbringer::Commands
 
   def read_keyboard_macro: (String) -> String
 
-  def macro_foo: (?Integer) -> Integer
 
   def execute_keyboard_macro: (Array[untyped], ?Integer) -> Integer
 end

sig/lib/textbringer/controller.rbs

@@ -1,9 +1,9 @@
 class Textbringer::Controller
   def initialize: () -> void
 
-  def self.current=: (Textbringer::FakeController) -> Textbringer::FakeController
+  def self.current=: (Textbringer::Controller?) -> Textbringer::Controller?
 
-  def self.current: () -> Textbringer::FakeController
+  def self.current: () -> Textbringer::Controller?
 
   def close: () -> nil