Building on PR #3508 and PR #4393, which allowed ignoring 5 different cell 'errors'. Adding this new one should have been dead easy, but MS, in its own inscrutable way, decided to complicate this by making the xml attribute require its very own namespace, unlike any of its relatives.
There are supposed to be several ways to activate this tag. One is to enter a date in cell A1, then in cell B1 enter the formula `=A1`, and set B1's numeric format to `General`.
When I implemented IgnoredErrors (PR #3508), I dealt only with those that I understood well enough to come up with an example. I finally found an example for FormulaRange in the wild, so this PR adds it. Still unsupported are `calculatedColumn`, `emptyCellReferece`, `listDataValidation`, and `unlockedFormula`.
While we might never be able to have 100% of our code strict, we can at
the very least do it for all of our tests. This ensures that our tests
are using our API with the types as intended by the test author, and not
silently be cast to what our API requires.
* Add Ability to Ignore Cell Errors in Excel
Fix#1141, which had been closed as stale, but which I have reopened. Excel will show cells with certain "errors" with a green triangle in the upper left. The suggestion in the issue to use quotePrefix to suppress the numberStoredAsText error is ineffective. In Excel, the user can turn this indicator off for individual cells. Cells where this is turned off can be detected at read time, and PhpSpreadsheet will now process those. In addition, the user can explicitly set the ignored error as in Excel.
```php
$cell->setIgnoredErrorNumberStoredAsText(true);
```
There are a number of different errors that can be ignored in this fashion. This PR implements `numberStoredAsText` (which is likely to be by far the most useful one), `formula`, `twoDigitTextYear`, and `evalError`, all of which are demonstrated in the new test spreadsheet. There are several others for which I am not able to create good examples; I have not implemented those, but they can be easily added if needed (`calculatedColumn`, `emptyCellReference`, `formulaRange`, `listDataValidation`, and `unlockedFormula`).
* Scrutinizer
A new change, a new Scrutinizer false positive.
* Move Ignored Errors to Own Class
In response to comments from @MarkBaker, implement ignoredError as a new class. This simplifies Cell by requiring only 1 new method, rather than 8+. This requires a slightly more complicated syntax.
```php
$cell->getIgnoredErrors()->setNumberScoredAsText(true);
```
Mark had also suggested that there might be a pre-existing regexp for processing the cells/cellranges when reading the sqref attribute. Those in Calculation are too complicated (read "non-performant") for this piece of code; the one in Coordinates is slightly less complicated than Calculation, but still more complicated than the one I'm using, and doesn't handle ranges.