…nd `BrowserHistoryIsOnLastPage`

…sOnFirstPage` and `BrowserHistoryIsOnLastPage` (santysisi)

This PR was merged into the 7.4 branch.

Discussion
----------

[BrowserKit] Add PHPUnit constraints: `BrowserHistoryIsOnFirstPage` and `BrowserHistoryIsOnLastPage`

| Q             | A
| ------------- | ---
| Branch?       | 7.4
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | no
| Issues        | no
| License       | MIT

This PR introduces two new PHPUnit constraints to improve testing of browser navigation history state:

- `BrowserHistoryIsOnFirstPage`
- `BrowserHistoryIsOnLastPage`

These constraints allow asserting the current state of the `AbstractBrowser` history using the following new assertion methods:

```php
$this->assertBrowserHistoryIsOnFirstPage();
$this->assertBrowserHistoryIsNotOnFirstPage();
$this->assertBrowserHistoryIsOnLastPage();
$this->assertBrowserHistoryIsNotOnLastPage();
```

Commits
-------

76e80c17237 [BrowserKit] Add PHPUnit constraints: `BrowserHistoryIsOnFirstPage` and `BrowserHistoryIsOnLastPage`

https://www.php.net/manual/en/language.types.string.php#language.types.string.syntax.heredoc