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, $new);
}
}
}
```
After this PR, there will be one more, with a small number of test changes, and enabling PhpUnit 10 for Php 8.1+.
* Permit Date/Time Entered on Spreadsheet to be Calculated as Float
Fix#1416. I do not entirely understand the use case for this old issue, but resolving it seems straightforward. Issue complains that user-entered date/time fields may be interpreted as either float or int when PhpSpreadsheet reads them. Issue suggests getCalculatedValue treat all date/time fields as float; that seems like a breaking change. However, adding an option to permit it seems okay. That option might be implemented as either a property of Calculation, or a static property of Cell. Since the changed logic is found in Cell (and Shared/Date), I opted for the latter.
In Cell, the property `$parent` is incorrectly described in doc block as `Cells`, and should be `?Cells`. This change eliminates some Phpstan and Scrutinizer problems, and should allow the elimination of some try/catch blocks - I have not done an exhaustive search for those.
Calls to `isDateTime` could have affected activeSheet and selectedCells; they no longer can. Optional parameters are added to it and the functions it calls to accommodate the new functionality; the defaults for the new parameters will, of course, return the same result as the earlier versions of the functions would have returned.
* Scrutinizer - Self-inflicted
Tests used constant which I deprecated.
oleibman