Improve breadcrumbs

• Improve design a little (lighter background, alignment with logo in nav bar, color, same font-weight for badge and text, etc.)
• Simplify code (single return, functional component, etc.)
• Fix first breadcrumb on "Closed Data", "Open Data" and "My Data" pages.
• Remove link from last breadcrumbs (it's not used by Bootstrap anyway because the last breadcrumb is always active) and from first breadcrumbs when the first breadcrumb points to the current page.
• If a breadcrumb in the path does not have a link, disable the breadcrumb and make sure it doesn't look clickable (e.g. "My Data", "Manager", etc.)
• Simplify passing true boolean props throughout the app: myProp={true} can be shortened to myProp.