Implements markets endpoint

[hayribakici]

This PR implements the v1/markets endpoint. In order to prevent errors as such, the country codes are stored in an enum

[rinukkusu]

Not a big fan of the CountryCode class. Way too much logic and code for what Spotify exposes. We simply get back a (list of) string. We don't need to convert between different ISO representations. I'm not sure it's even necessary to abstract this result more.

What would be the gain of such a class?

[hayribakici]

Not a big fan of the CountryCode class. Way too much logic and code for what Spotify exposes. We simply get back a (list of) string. We don't need to convert between different ISO representations. I'm not sure it's even necessary to abstract this result more.

What would be the gain of such a class?

Pretty much abstraction and preventing errors when handling with country codes, just as we use the enums in our library. What do you think about an enum with country codes?

[hayribakici]

@rinukkusu I changed the result-type to an enum. I wanted to keep a fixed structure to prevent any type of error. This could also make the usage of the library easier by putting a Market parameter into certain methods:

BundledPages get(
    String searchQuery, {
    Iterable<SearchType> types = SearchType.all,
    Market? market,
  }) {...

Of course I can change it, when you still think it is unnecessary. 😆

[rinukkusu]

Hi, sorry for being MIA - I was on vacation 😆
I think the enum is a very good middleground! And of course, then we should also use it in other places.

[rinukkusu]

LGTM!