named_type: forbid arithmetic operations between unrelated named_types

[andijcr]

explicitly forbids operations like

named_type<int, struct tag_a>(1) + named_type<int, struct tag_b>(1)

The expression worked because there is an implicit conversion possible from named_type<int, tag> to int, and an operator+(int).

this pr deletes the generic base_named_type from the arithmetic operators overload set and implicitly forbids the above case to compile.

operations like

named_type<int>(1) + 1

are still allowed. see named_type_test.cc

template<typename Lhs, typename Rhs>
concept arithmetic_ready = requires(Lhs l, Rhs r) {
    l + r;
    l - r;
    l += r;
};

static_assert(arithmetic_ready<named_int, named_int>);
static_assert(arithmetic_ready<named_int, int>);
static_assert(
  !arithmetic_ready<named_int, named_type<int, struct another_tag_t>>);

Backports Required

• [ ] none - not a bug fix
• [ ] none - this is a backport
• [ ] none - issue does not exist in previous branches
• [x] none - papercut/not impactful enough to backport
• [ ] v23.2.x
• [ ] v23.1.x
• [ ] v22.3.x

Release Notes

• none