Read conditional styling for cell (#2491)

* Allow single-cell checks on conditional styles, even when the style is configured for a range of cells
* Work on the CellMatcher logic to evaluate Conditionals for a cell based on its value, and identify which conditional styles should be applied
* Refactor style merging and cell matching for conditional formatting into separate classes; this should make it easier to test, and easier to extend for other CF expressions subsequently
* Added support for containsErrors and notContainsErrors
* Initial work on a wizard to help simplify created Conditional Formatting rules, to ensure that the correct expressions are set
* Further work on extending the Conditional Formatting rules to cover more of the options that are available in MS Excel
* Prevent phpcs-fixer from removing class @method annotations, used to identify the signature for magic methods used in Wizard classes
* Implement `fromConditional()`` method to allow the creation of a CF Wizard from an existing Conditional
* Ensure that xlsx Reader picks up the timePeriod attribute for DatesOccurring CF Rules
* Allow Duplicates/Uniques CF Rules to be recognised in the Xlsx Reader
* Basic Xlsx reading of CF Rules/Styles from <extLst><ext><ConditinalFormattings> element, and not just the <ConditinalFormatting> element of the worksheet

* Add some validation for operands passed to the CF Wizards
 - remove any leading ``=` from formulae, because they'll be embedded into other formulae
 - unwrap any string literals from quotes, because that's also handled internally

Handle cross-worksheet cell references in cellReferences and Formulae/Expressions

* re-baseline phpstan

* Update Change Log with details of the CF Improvements

samples/ConditionalFormatting/04_Error_Comparisons.php

@@ -0,0 +1,79 @@
+<?php
+
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PhpOffice\PhpSpreadsheet\Style\Color;
+use PhpOffice\PhpSpreadsheet\Style\ConditionalFormatting\Wizard;
+use PhpOffice\PhpSpreadsheet\Style\Fill;
+use PhpOffice\PhpSpreadsheet\Style\Style;
+
+require __DIR__ . '/../Header.php';
+
+// Create new Spreadsheet object
+$helper->log('Create new Spreadsheet object');
+$spreadsheet = new Spreadsheet();
+
+// Set document properties
+$helper->log('Set document properties');
+$spreadsheet->getProperties()->setCreator('Mark Baker')
+    ->setLastModifiedBy('Mark Baker')
+    ->setTitle('PhpSpreadsheet Test Document')
+    ->setSubject('PhpSpreadsheet Test Document')
+    ->setDescription('Test document for PhpSpreadsheet, generated using PHP classes.')
+    ->setKeywords('office PhpSpreadsheet php')
+    ->setCategory('Test result file');
+
+// Create the worksheet
+$helper->log('Add data');
+$spreadsheet->setActiveSheetIndex(0);
+$spreadsheet->getActiveSheet()
+    ->setCellValue('A1', 'Error Comparison');
+
+$dataArray = [
+    [5, -2, '=A2/B2'],
+    [5, -1, '=A3/B3'],
+    [5, 0, '=A4/B4'],
+    [5, 1, '=A5/B5'],
+    [5, 2, '=A6/B6'],
+];
+
+$spreadsheet->getActiveSheet()
+    ->fromArray($dataArray, null, 'A2', true);
+
+// Set title row bold
+$helper->log('Set title row bold');
+$spreadsheet->getActiveSheet()->getStyle('A1:C1')->getFont()->setBold(true);
+
+// Define some styles for our Conditionals
+$helper->log('Define some styles for our Conditionals');
+$greenStyle = new Style(false, true);
+$greenStyle->getFill()
+    ->setFillType(Fill::FILL_SOLID)
+    ->getEndColor()->setARGB(Color::COLOR_GREEN);
+$redStyle = new Style(false, true);
+$redStyle->getFill()
+    ->setFillType(Fill::FILL_SOLID)
+    ->getEndColor()->setARGB(Color::COLOR_RED);
+
+// Set conditional formatting rules and styles
+$helper->log('Define conditional formatting and set styles');
+
+// Set rules for Blank Comparison
+$cellRange = 'C2:C6';
+$conditionalStyles = [];
+$wizardFactory = new Wizard($cellRange);
+/** @var Wizard\Errors $errorsWizard */
+$errorsWizard = $wizardFactory->newRule(Wizard::ERRORS);
+
+$errorsWizard->setStyle($redStyle);
+$conditionalStyles[] = $errorsWizard->getConditional();
+
+$errorsWizard->notError()
+    ->setStyle($greenStyle);
+$conditionalStyles[] = $errorsWizard->getConditional();
+
+$spreadsheet->getActiveSheet()
+    ->getStyle($errorsWizard->getCellRange())
+    ->setConditionalStyles($conditionalStyles);
+
+// Save
+$helper->write($spreadsheet, __FILE__);