fix: fix type definitions about last column, formula values and protection

[gltjk]

Summary

Several type definition has been fixed. Details:

• Worksheet.lastColumn can be undefined for an empty worksheet, as Worksheet.lastRow can be undefined.
• date1904 should be an optional property for both CellFormulaValue and CellSharedFormulaValue.
• CellFormulaValue.result and CellSharedFormulaValue.result should include boolean.
• CellFormulaValue.result and CellSharedFormulaValue.result should include CellErrorValue, not { error: CellErrorValue }, because CellErrorValue itself is already an interface with error as its property.
• Protection should have a hidden property, as is recorded in the documentation.
• dashed should be a valid value for BorderStyle, as is documented in ISO/IEC 29500-1:2016 18.18.3 ST_BorderStyle (Border Line Styles).

Test plan

Related to source code (for typings update)

• exceljs/index.d.ts

  Lines 1188 to 1191 in ec92cb3

  	/**
  	* Get the last editable row in a worksheet (or undefined if there are none)
  	*/
  	readonly lastRow: Row | undefined;

• exceljs/lib/xlsx/xform/sheet/cell-xform.js

  Lines 95 to 99 in ec92cb3

  	case Enums.ValueType.Formula:
  	if (options.date1904) {
  	// in case valueType is date
  	model.date1904 = true;
  	}

• exceljs/lib/xlsx/xform/sheet/cell-xform.js

  Lines 354 to 355 in ec92cb3

  	} else if (this.t === 'b') {
  	model.result = parseInt(model.value, 10) !== 0;

• exceljs/lib/xlsx/xform/sheet/cell-xform.js

  Lines 356 to 357 in ec92cb3

  	} else if (this.t === 'e') {
  	model.result = {error: model.value};

• exceljs/lib/xlsx/xform/style/protection-xform.js

  Lines 42 to 45 in ec92cb3

  	const model = {
  	locked: !(node.attributes.locked === '0'),
  	hidden: node.attributes.hidden === '1',
  	};

[Siemienik]

LGTM, thanks