Revert "Use the new appendURLString function in WordPressComRestApi"

[crazytonyli]

Description

This PR reverts b01de44 due to an strange usage of WordPressComRestApi.get(path:) function.

WordPressKit-iOS/WordPressKit/ReaderPostServiceRemote.m

Lines 198 to 204 in ae8f83e

	- (void)fetchPostsFromEndpoint:(NSURL *)endpoint
	withParameters:(NSDictionary *)params
	success:(void (^)(NSArray<RemoteReaderPost *> *posts, NSString *algorithm))success
	failure:(void (^)(NSError *))failure
	{
	NSString *path = [endpoint absoluteString];
	[self.wordPressComRestApi GET:path

As you can see in the snippet above, a full URL (i.e. https://public-api.wordpress.com/rest/v1.2/read/liked) is used as a path argument. IMO, this is an illegal use case (Gio has kindly create a fix for that in #727) which sends an correct HTTP requests.

Considering the commit b01de44 does break an use case in the app, and who knows what other strange "path" argument the app may pass, I'll revert the commit for now (to prevent it from being shipped in next release) and fix the illegal use case properly in separate PRs.

Testing Details

See the added unit tests.

---

• Please check here if your pull request includes additional test coverage.
• I have considered if this change warrants release notes and have added them to the appropriate section in the CHANGELOG.md if necessary.

[mokagio]

Love the addition of a unit test 💪

Considering the commit b01de44 does break an use case in the app, and who knows what other strange "path" argument the app may pass, I'll revert the commit for now (to prevent it from being shipped in next release) and fix the illegal use case properly in separate PRs.

That seems very wise. I was pleased that the WordPress UI tests caught this issue. But I don't feel confident in the tests coverage to say that all issues related to this have been addressed 😞