Replace renderXYZ methods with slots

[MarcusNotheis]

UI5 Web Components for React used to have renderXYZ props for adding custom content into components, e.g. renderCustomHeader. The UI5 Web Components are using slots for achieving the same goal.
For providing a unified API, we should deprecate the renderMethods in 0.9 and remove them finally in 0.10.

Affected Components

• AnalyticalTable: renderExtension
• Bar: renderContentLeft, renderContentMiddle, renderContentRight
• FilterBar: renderVariants, renderSearch
• ObjectPage: renderHeaderContent, renderBreadcrumbs, renderKeyInfos
• Page: renderCustomHeader, renderCustomFooter