Fix incorrect result for Base.invmod(<:Signed, <:Unsigned) (#58010)

MWE of bug:
```julia
julia> Int(invmod(1024, UInt(12289)))
5652

julia> invmod(1024, 12289)
12277
```

---------

Co-authored-by: Max Horn <max@quendi.de>
Co-authored-by: Lilith Orion Hafner <lilithhafner@gmail.com>

Author: 3 people

base/intfuncs.jl

@@ -286,7 +286,7 @@ function invmod(n::Integer, m::Integer)
     g, x, y = gcdx(n, m)
     g != 1 && throw(DomainError((n, m), LazyString("Greatest common divisor is ", g, ".")))
     # Note that m might be negative here.
-    if n isa Unsigned && hastypemax(typeof(n)) && x > typemax(n)>>1
+    if x isa Unsigned && hastypemax(typeof(x)) && x > typemax(x)>>1
         # x might have wrapped if it would have been negative
         # adding back m forces a correction
         x += m

test/intfuncs.jl

@@ -258,6 +258,13 @@ end
         @test invmod(T(3), T(124))::T == 83
     end
 
+    for T in (Int8, Int16, Int32, Int64, Int128)
+        @test invmod(T(3), unsigned(T)(124)) == 83
+    end
+
+    # Verify issue described in PR 58010 is fixed
+    @test invmod(UInt8(3), UInt16(50000)) === 0x411b
+
     for T in (Int8, UInt8)
         for x in typemin(T):typemax(T)
             for m in typemin(T):typemax(T)