All public types implement Debug trait

[oguzkocer]

Builds on #108.

Rust API Guidelines - Debuggability states:

All public types implement Debug (C-DEBUG)
If there are exceptions, they are rare.

I've gone through all our public types and derived Debug trait. If there are any that doesn't derive it, it's just because I missed it. I've also added custom implementations for WPNetworkRequest & WPNetworkResponse types, so body can be printed as a String and in a nice-ish format.

It adds the indoc crate to make it easier to work with multiline strings. I wouldn't add the crate just for this implementation, but I think we'll utilize it more. It's also a tiny crate.

Here are some examples:

println!(
    "{:?}",
    api().create_user_request(&UserCreateParams::new(
        "foo".to_string(),
        "foo@example.com".to_string(),
        "strong_foo".to_string(),
    ))
);
---
WPNetworkRequest {
    method: 'POST',
    url: 'http://localhost/wp-json/wp/v2/users',
    header_map: '{"accept": "application/json", "content-type": "application/json", "Authorization": "Basic dGVzdEBleGFtcGxlLmNvbTo1TU9rSnlCVVo3OHdUSVdES2FhcHpGS1k="}',
    body: 'Some("{\"username\":\"foo\",\"email\":\"foo@example.com\",\"password\":\"strong_foo\"}")'
}

println!(
    "{:?}",
    api().retrieve_user_request(FIRST_USER_ID, WPContext::Edit)
);
---
WPNetworkRequest {
    method: 'GET',
    url: 'http://localhost/wp-json/wp/v2/users/1?context=edit',
    header_map: '{"accept": "application/json", "Authorization": "Basic dGVzdEBleGFtcGxlLmNvbTo1TU9rSnlCVVo3OHdUSVdES2FhcHpGS1k="}',
    body: 'None'
}

println!(
    "{:?}",
    api()
        .retrieve_user_request(FIRST_USER_ID, WPContext::Edit)
        .execute()
        .await
);
---
Ok(WPNetworkResponse {
    status_code: '200',
    header_map: 'None',
    body: '{"id":1,"username":"test@example.com","name":"test@example.com","first_name":"","last_name":"","email":"test@example.com","url":"http:\/\/localhost","description":"","link":"http:\/\/localhost\/author\/testexample-com\/","locale":"en_US","nickname":"test@example.com","slug":"testexample-com","roles":["administrator"],"registered_date":"2024-05-23T17:20:09+00:00","capabilities":{"switch_themes":true,"edit_themes":true,"activate_plugins":true,"edit_plugins":true,"edit_users":true,"edit_files":true,"manage_options":true,"moderate_comments":true,"manage_categories":true,"manage_links":true,"upload_files":true,"import":true,"unfiltered_html":true,"edit_posts":true,"edit_others_posts":true,"edit_published_posts":true,"publish_posts":true,"edit_pages":true,"read":true,"level_10":true,"level_9":true,"level_8":true,"level_7":true,"level_6":true,"level_5":true,"level_4":true,"level_3":true,"level_2":true,"level_1":true,"level_0":true,"edit_others_pages":true,"edit_published_pages":true,"publish_pages":true,"delete_pages":true,"delete_others_pages":true,"delete_published_pages":true,"delete_posts":true,"delete_others_posts":true,"delete_published_posts":true,"delete_private_posts":true,"edit_private_posts":true,"read_private_posts":true,"delete_private_pages":true,"edit_private_pages":true,"read_private_pages":true,"delete_users":true,"create_users":true,"unfiltered_upload":true,"edit_dashboard":true,"update_plugins":true,"delete_plugins":true,"install_plugins":true,"update_themes":true,"install_themes":true,"update_core":true,"list_users":true,"remove_users":true,"promote_users":true,"edit_theme_options":true,"delete_themes":true,"export":true,"administrator":true},"extra_capabilities":{"administrator":true},"avatar_urls":{"24":"http:\/\/2.gravatar.com\/avatar\/55502f40dc8b7c769880b10874abc9d0?s=24&d=mm&r=g","48":"http:\/\/2.gravatar.com\/avatar\/55502f40dc8b7c769880b10874abc9d0?s=48&d=mm&r=g","96":"http:\/\/2.gravatar.com\/avatar\/55502f40dc8b7c769880b10874abc9d0?s=96&d=mm&r=g"},"meta":{"persisted_preferences":[]},"_links":{"self":[{"href":"http:\/\/localhost\/wp-json\/wp\/v2\/users\/1"}],"collection":[{"href":"http:\/\/localhost\/wp-json\/wp\/v2\/users"}]}}'
})

[jkmassel]

I thought about suggesting a DRY thing for the multi-line strings, but they're rare enough that I think we can go back and do it later.