Formula: Update type signatures

We're seeing type errors when building formulae that use something
like `xcodebuild ..., "-arch", Hardware::CPU.arch`, since `CPU.arch`
is a symbol. We've been addressing these issues by calling `#to_s` on
the value but there was some talk about simply expanding the type
signatures to accommodate anything that will be cast to a `String`.

There's maybe still an argument to be made for doing string conversion
in formulae but expanding the type signatures will resolve a number of
existing type errors if we simply want to rely on implicit type
casting.

Library/Homebrew/formula.rb

@@ -2629,7 +2629,7 @@ def undeclared_runtime_dependencies
   #
   # # If there is a "make install" available, please use it!
   # system "make", "install"</pre>
-  sig { params(cmd: T.any(String, Pathname), args: T.any(String, Pathname, Integer)).void }
+  sig { params(cmd: T.any(String, Pathname), args: T.any(String, Integer, Pathname, Symbol)).void }
   def system(cmd, *args)
     verbose_using_dots = Homebrew::EnvConfig.verbose_using_dots?
 
@@ -2794,7 +2794,7 @@ def mkdir(name, &block)
   end
 
   # Runs `xcodebuild` without Homebrew's compiler environment variables set.
-  sig { params(args: T.any(String, Pathname)).void }
+  sig { params(args: T.any(String, Pathname, Symbol)).void }
   def xcodebuild(*args)
     removed = ENV.remove_cc_etc