Error Helpers

[EvanLF6768]

Common operations and interfaces should have a well defined way in which they can fail (likely using std::expected). It should be possible to propagate errors up through functions with some sort of compound error object (combination of context and inner) in a concise manner. For example:

enum class WangleError {
    kCantGetFoo,
    kWanglingByZero,
};
auto Wangle() -> std::expected<int, obc::error::Error<
    obc::error::Case<WangleError::kCantGetFoo, decltype(GetFoo())::error_type>,
    obc::error::Case<WangleError::kWanglingByZero>
>> {
    auto foo = GetFoo();
    if (!foo) return obc::error::Fail(WangleError::kCantGetFoo, foo);
    // Use the value of foo
}

bugprone-unchecked-optional-access must be expanded to work with std::expected.