Create and initialize the TestStore inside InitializeAsync

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Before this commit, it was impossible to create a concrete implementation of SharedStoreFixtureBase that requires a TestStoreFactory which is initialized asynchronously (the purpose of IAsyncLifetime).

After this commit, it becomes possible because the TestStoreFactory and the StoreName properties are not accessed in the constructor anymore:

public class MySharedStoreFixture<TContext> : SharedStoreFixtureBase<TContext> where TContext : DbContext
{
    private string? _storeName;
    private ITestStoreFactory? _testStoreFactory;

    protected override string StoreName => _storeName ?? throw new InvalidOperationException($"The {nameof(StoreName)} property is only available after {nameof(InitializeAsync)} has executed.");
    protected override ITestStoreFactory TestStoreFactory => _testStoreFactory ?? throw new InvalidOperationException($"The {nameof(TestStoreFactory)} property is only available after {nameof(InitializeAsync)} has executed.");

    public override async Task InitializeAsync()
    {
        var someInfo = await GetSomeInfoAsync();

        _storeName = someInfo.Name;
        _testStoreFactory = new MyTestStoreFactory(someInfo);

        await base.InitializeAsync();
    }
}

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Ping @AndriySvyryd

[AndriySvyryd]

@0xced Please rebase this on release/5.0-rc2

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I just rebased on release/5.0-rc2, let's see if all tests passes like they did on main. 🤞🏻

[AndriySvyryd]

@Pilchie FYI

[AndriySvyryd]

@0xced Thanks for your contribution