Added missing migration methods

[papafe]

This PR adds two methods that were missing on Migration: RemoveType and RenameProperty.

Description

Fixes #2543

TODO

• Changelog entry
• Tests (if applicable)

[DominicFrei]

Do we need to differentiate between the (general) schema and the object schema to not confuse anyone here?

[papafe]

I think it's clear enough with the "its", but maybe it's not?

[DominicFrei]

Clear enough for me because I know how Realm works and what the difference between a schema and an object schema is. Then again, how important is this for a user? They just want to use the framework and not understand too much about the internals I suppose. I guess it's fine both ways. ;)

[DominicFrei]

Don't see anything wrong with that. :) Just added two questions for clarification.

[papafe]

A question is... Do we want the two method to work in the same way for what regards using a type that is not in the schema?
RemoveType will return false, while RenameProperty will likely throw an exception. I suppose the reason why it was done for the first and not for the second in Cocoa (where I took inspiration) is because for the first method we need to retrieve the table anyway to execute the method.

[nirinchev]

Removing a type that no longer exists (or never existed) is probably not an exception-worthy situation. You do end up in the same state - a Realm without this particular type. Renaming a property that didn't exist vs one that did exist is different as you would expect to have some data appear in your new Realm - that's the main point of using RenameProperty vs just deleting the old one and adding the new one. So if it turns out you're trying to rename something non-existent, that's likely a mistake and we should let you know.

[DominicFrei]

The non-throwing delete would also be in line with other deletes. Take DeleteRealm for example. If the Realm was already deleted, it's fine, we just accept that because the goal was that that Realm does not exist anymore. Throwing an exception would be like throwing an exception just because the Realm we try to delete did not exist in the first place.

[nirinchev]

I have a couple of comments mostly around code style and docs, but for the most part it looks good. What is missing outside of the comments I added is:

1. Tests for invalid arguments (null, empty strings, a string with 1000 characters)
2. A test for renaming a property to a value that doesn't exist in the new schema
3. Address the build warnings/CodeQL errors

[nirinchev]

Can you rebase on master? There was a Coveralls outage over the weekend which is why the base coverage report is missing.

[coveralls]

Pull Request Test Coverage Report for Build 1286514500

• 17 of 17 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.05%) to 74.388%

---

Totals
Change from base Build 1271688483:	0.05%
Covered Lines:	4582
Relevant Lines:	6142

---

💛 - Coveralls

[papafe]

Final corrections done (lint correction, more tests, ...)

[nirinchev]

Good job!