## Have item at index

You can verify that the collection contains an item that satisfies the expectation on a given index (or any index).

```csharp
IEnumerable<string> values = ["0th item", "1st item", "2nd item", "3rd item"];

await Expect.That(values).HasItem("1st item").AtIndex(1);
await Expect.That(values).HasItem(a => a.StartsWith("2nd")).AtAnyIndex();
```

*Note: The same expectation works also for `IAsyncEnumerable<T>`.*

Also update aweXpect to v2.19.1 and change build scope to "Default"

This PR enhances the `HasItem` functionality to provide specialized string comparison capabilities, moving from generic object comparison to dedicated string-specific operations. The implementation adds comprehensive string matching options including prefix, suffix, wildcard, regex patterns, and various whitespace/case handling options.

- Introduces `StringHasItemResult` classes for specialized string item verification with rich comparison options
- Adds string-specific `HasItem` overloads for both sync and async enumerables, including `ImmutableArray<string?>`
- Refactors existing `ObjectHasItemResult` to implement `IOptionsProvider` interface and moves `Equivalent` method to an extension method

You can now also use expectations on the individual items.

```csharp
IEnumerable<string> values = ["0th item", "1st item", "2nd item", "3rd item"];

await Expect.That(values).HasItemThat(it => it.IsEqualTo("1st item")).AtIndex(1);
await Expect.That(values).HasItemThat(it => it.StartsWith("2nd").And.EndsWith("item")).AtAnyIndex();
```

*Note: The same expectation works also for `IAsyncEnumerable<T>`.*

This PR updates the aweXpect.Core package from version 2.15.0 to 2.15.1 and adjusts the build scope configuration accordingly.

- Updates aweXpect.Core package version to 2.15.1
- Changes BuildScope from CoreOnly back to Default

…emThat` (#687)

This PR simplifies the collection item verification API by removing the need to explicitly call `.AtAnyIndex()` after `HasItem()` or `HasItemThat()` methods. The change makes the API more intuitive by defaulting to checking items at any index while still allowing specific index checks with `.AtIndex(index)`.

- Refactored `HasItemResult<TCollection>` to inherit from `AndOrResult` and removed the `AtAnyIndex()` method
- Updated all test cases to remove `.AtAnyIndex()` calls, making them more concise
- Updated API documentation and usage examples to reflect the simplified syntax

This PR updates the aweXpect.Core package to version 2.15.2 and re-enables the full build scope by changing from CoreOnly to Default, which aligns with the typical workflow after package updates are completed.

- Updates aweXpect.Core package reference from version 2.15.1 to 2.15.2
- Changes BuildScope from CoreOnly back to Default to enable full build pipeline