Successor to PR #3523. There are 494 single-line changes (`public function provider` to `public static function provider`) in this PR. None of these were made manually; they were all created with the following script (adapted from
https://stackoverflow.com/questions/25909820/how-to-recursively-iterate-through-files-in-php):
```php
$dir = 'C:/git/unit10prep2/tests/PhpSpreadsheetTests';
$it = new RecursiveDirectoryIterator($dir);
// Loop through files
foreach(new RecursiveIteratorIterator($it) as $file) {
if ($file->getExtension() === 'php') {
$contents = file_get_contents($file);
$new = preg_replace('/public function (\\w*)([Pp])rovider/', 'public static function $1$2rovider', $contents);
if ($new !== $contents) {
echo "changing $file\n";
file_put_contents($file, $new);
}
}
}
```
After this PR, there will be one more, with a small number of test changes, and enabling PhpUnit 10 for Php 8.1+.
Scrutinizer had previously suggested annotations for 3 LookupRef tests, but it no longer accepts its own annotation for those cases. This PR cleans them up. ColumnsTest and RowsTest are extremely straightforward.
IndexTest is a bit more complicated, but only because, unlike the other two, it had no test which executed in the context of a spreadsheet. And, when I added those, I discovered a couple of bugs. INDEX always requires at least 2 parameters (row# is always required), but its entry in the function table specified 1-4 parameters, now changed to 2-4. And, omitting col# is not handled the same way as specifying 0 for col#, though the code had treated them identically. (The same would have been true for row# but, because it is now required, ...)
oleibman