add export feature to HTML

[jochenwezel]

• Epplus 4.5 CM-Edition Engine
• Epplus Polyform Engine
• MSExcelInterop Engine
• FreeSpireXls Engine
• SpireXls Engine

[jochenwezel]

More ToDos

• at Epplus engines: color scheme with their accent color values not considered correctly
• at all other engines: check for color scheme with their accent color values not considered correctly

[jochenwezel]

Additional follow-up from the API documentation cleanup: the remaining documentation work for the HTML export API was intentionally left out of the general cleanup and should be handled as part of this ticket.

Current temporary checker exclusions for this ticket:

• ExcelOps/ExcelOpsLowLevel/HtmlSheetExportOptions.vb
• ExcelOps/ExcelOpsLowLevel/HtmlWorkbookExportOptions.vb
• ExcelOps/ExcelOpsLowLevel/ExcelDataOperationsBase.vb: HtmlDocumentExportParts

ToDo for this ticket:

• Review and complete XML documentation for the HTML export option/API surface.
• Revisit the HTML export API shape while implementing the remaining engine support.
• Remove the temporary API documentation checker exclusions once the HTML export API documentation is complete.