LibCrypto: Make the constructors of (Un)SignedBigInteger templated

This means it can take any (un)signed word of size at most Word.
This means the constructor can be disambiguated if we were to add a
double constructor :^).

This requires a change in just one test.

Userland/Libraries/LibCrypto/BigInt/SignedBigInteger.h

@@ -16,9 +16,11 @@ struct SignedDivisionResult;
 
 class SignedBigInteger {
 public:
-    SignedBigInteger(i32 x)
-        : m_sign(x < 0)
-        , m_unsigned_data(abs(x))
+    template<typename T>
+    requires(IsSigned<T> && sizeof(T) <= sizeof(i32))
+        SignedBigInteger(T value)
+        : m_sign(value < 0)
+        , m_unsigned_data(abs(static_cast<i32>(value)))
     {
     }