Base: power_by_squaring: don't require one

* Follows up on/partially reverts JuliaLang#55634
* Reopens JuliaLang#53504, perhaps it's OK to require some types to implement
  their own `^`
* Fixes JuliaLang#57390, a regression

base/intfuncs.jl

@@ -336,7 +336,7 @@ end
 
 # ^ for any x supporting *
 function to_power_type(x::Number)
-    T = promote_type(typeof(x), typeof(one(x)), typeof(x*x))
+    T = promote_type(typeof(x), typeof(x*x))
     convert(T, x)
 end
 to_power_type(x) = oftype(x*x, x)